Aluminum is used for the production of products and alloys based on it.

Alloying is the process of introducing additional elements into the melt that improve the mechanical, physical and chemical properties of the base material. Alloying is a general concept of a number of technological procedures carried out at various stages of obtaining a metallic material in order to improve the quality of metallurgical products.

Introduction of various alloying elements in aluminum significantly changes its properties, and sometimes gives it new specific properties.

The strength of pure aluminum does not satisfy modern industrial needs, therefore, for the manufacture of any products intended for industry, not pure aluminum is used, but its alloys.

With different doping increase strength, hardness, heat resistance is acquired and other properties. At the same time, undesirable changes also occur: the electrical conductivity, worsens in many cases corrosion resistance, almost always increases relative density. The exception is alloying with manganese, which not only does not reduce corrosion resistance, but even slightly increases it, and magnesium, which also increases corrosion resistance (if it is not more than 3%) and reduces relative density, since it is lighter than aluminum.

Aluminum alloys

Aluminum alloys according to the method of manufacturing products from them are divided into two groups:
1) deformable (have high ductility when heated),
2) foundry (have good fluidity).

This division reflects the main technological properties of the alloys. To obtain these properties, aluminum is introduced with various alloying elements and in different quantities.

The raw materials for obtaining alloys of both types are not only commercially pure aluminum, but also aluminum-silicon binary alloys, which contain 10-13% Si, and differ slightly from each other in the amount of impurities of iron, calcium, titanium and manganese. The total content of impurities in them is 0.5-1.7%. These alloys are called silumins. In order to obtain wrought alloys, alloying elements soluble in it are mainly introduced into aluminum in an amount not exceeding the limit of their solubility at high temperature. Wrought alloys when heated under pressure treatment should have a homogeneous solid solution structure, providing the highest ductility and the lowest strength. This determines their good workability by pressure.

The main alloying elements in various wrought alloys are copper, magnesium, manganese and zinc, in addition, silicon, iron, nickel and some other elements are also introduced in relatively small quantities.

Duralumin - aluminum alloys with copper

Characteristic hardenable alloys are duralumin - alloys of aluminum with copper, which contain constant impurities of silicon and iron and can be alloyed with magnesium and manganese. The amount of copper in them is in the range of 2.2-7%.

Copper dissolves in aluminum in an amount of 0.5% at room temperature and 5.7% at a eutectic temperature of 548 C.

Heat treatment of duralumin consists of two stages. First, it is heated above the limiting solubility line (usually up to about 500 C). At this temperature, its structure is a homogeneous solid solution of copper in aluminum. By hardening, i.e. rapid cooling in water, this structure is fixed at room temperature. In this case, the solution becomes supersaturated. In this state, i.e. in a state of hardening, duralumin is very soft and ductile.

The structure of hardened duralumin has little stability, and even at room temperature changes spontaneously occur in it. These changes come down to the fact that excess copper atoms are grouped in solution, arranged in an order close to that characteristic of crystals of the chemical compound CuAl. The chemical compound is not yet formed and, moreover, is not separated from the solid solution, but due to the uneven distribution of atoms in the crystal lattice of the solid solution, distortions occur in it, which lead to a significant increase in hardness and strength with a simultaneous decrease in the ductility of the alloy. The process of changing the structure of a hardened alloy at room temperature is called natural aging.

Natural aging occurs especially intensively during the first few hours, but it is completely completed, giving the alloy its maximum strength, after 4-6 days. If the alloy is heated to 100-150 C, then artificial aging. In this case, the process is completed quickly, but the hardening occurs less. This is explained by the fact that at a higher temperature, the diffusion displacements of copper atoms are carried out more easily; therefore, the formation of the CuAl phase is completed and it is separated from the solid solution. The strengthening effect of the obtained phase turns out to be less than the effect of the distortion of the solid solution lattice that occurs during natural aging.

Comparison of the results of aging of duralumin at different temperatures shows that the maximum hardening is provided during natural aging within four days.

Alloys of aluminum with manganese and magnesium

Among non-hardenable aluminum alloys, alloys based on Al-Mn and Al-Mg have gained the most importance.

manganese and magnesium, as well as copper, have a limited solubility in aluminum, which decreases with decreasing temperature. However, the effect of hardening during their heat treatment is small. This is explained as follows. In the process of crystallization in the manufacture of alloys containing up to 1.9% Mn, excess manganese liberated from the solid solution should have formed with aluminum a chemical compound Al (MnFe) soluble in it, which does not dissolve in aluminum. Consequently, subsequent heating above the limiting solubility line does not ensure the formation of a homogeneous solid solution, the alloy remains heterogeneous, consisting of a solid solution and Al (MnFe) particles, and this leads to the impossibility of hardening and subsequent aging.

In the case of the Al-Mg system, the reason for the lack of hardening during heat treatment is different. With a magnesium content of up to 1.4%, there can be no hardening, since within these limits it dissolves in aluminum at room temperature and no precipitation of excess phases occurs. At a higher magnesium content, quenching followed by chemical aging leads to the release of an excess phase - the chemical compound MgAl.

However, the properties of this compound are such that the processes preceding its isolation, and then the resulting inclusions, do not cause a noticeable hardening effect. Despite this, the introduction of both manganese and magnesium in aluminum is beneficial. They increase its strength and corrosion resistance (with a magnesium content of not more than 3%). In addition, magnesium alloys are lighter than pure aluminum.

Other alloying elements

Also, to improve some of the characteristics of aluminum, the following are used as alloying elements:

Beryllium is added to reduce oxidation at elevated temperatures. Small additions of beryllium (0.01-0.05%) are used in aluminum casting alloys to improve fluidity in the production of internal combustion engine parts (pistons and cylinder heads).

Boron is introduced to increase electrical conductivity and as a refining additive. Boron is introduced into aluminum alloys used in nuclear power engineering (except for reactor parts), because it absorbs neutrons, preventing the spread of radiation. Boron is introduced on average in the amount of 0.095-0.1%.

Bismuth. Low melting point metals such as bismuth, lead, tin, cadmium are added to aluminum alloys to improve machinability. These elements form soft fusible phases that contribute to chip breakage and cutter lubrication.

Gallium is added in the amount of 0.01 - 0.1% to the alloys from which the sacrificial anodes are further made.

Iron. In small quantities (>0.04%), it is introduced during the production of wires to increase strength and improve creep characteristics. Iron also reduces sticking to the walls of molds when casting into a chill mold.

Indium. The addition of 0.05 - 0.2% strengthens aluminum alloys during aging, especially at low copper content. Indium additives are used in aluminium-cadmium bearing alloys.

Cadmium. Approximately 0.3% cadmium is added to increase the strength and improve the corrosion properties of the alloys.

Calcium gives plasticity. With a calcium content of 5%, the alloy has the effect of superplasticity.

Silicon is the most used additive in foundry alloys. In the amount of 0.5-4% reduces the tendency to cracking. The combination of silicon and magnesium makes it possible to heat seal the alloy.

Tin improves machining.

Titanium. The main task of titanium in alloys is grain refinement in castings and ingots, which greatly increases the strength and uniformity of properties throughout the volume.

Application of aluminum alloys

Most aluminum alloys have high corrosion resistance in the natural atmosphere, sea water, solutions of many salts and chemicals, and in most foods. The latter property, combined with the fact that aluminum does not destroy vitamins, allows it to be widely used. in the production of tableware. Aluminum alloy structures are often used in sea water. Aluminum is widely used in construction in the form of cladding panels, doors, window frames, and electrical cables. Aluminum alloys are not subject to severe corrosion for a long time in contact with concrete, mortar, plaster, especially if the structures are not frequently wet. Aluminum is also widely used in mechanical engineering, because has good physical qualities.

But the main industry, currently simply unthinkable without the use of aluminum, is, of course, aviation. It is in aviation that all the important characteristics of aluminum have been most fully used.

Physical properties of aluminum

Aluminum is a soft, light, silvery-white metal with high thermal and electrical conductivity. Melting point 660°C.

In terms of prevalence in the earth's crust, aluminum ranks 3rd after oxygen and silicon among all atoms and 1st among metals.

The advantages of aluminum and its alloys include its low density (2.7 g/cm3), relatively high strength characteristics, good thermal and electrical conductivity, manufacturability, and high corrosion resistance. The combination of these properties makes it possible to classify aluminum as one of the most important technical materials.

Aluminum and its alloys are divided according to the method of production into deformable, subjected to pressure treatment and foundry, used in the form of shaped casting; on the use of heat treatment - on thermally non-hardened and thermally hardened, as well as on alloying systems.

Receipt

Aluminum was first obtained by Hans Oersted in 1825. The modern method of obtaining was developed independently by the American Charles Hall and the Frenchman Paul Héroux. It consists in the dissolution of aluminum oxide Al2O3 in a melt of Na3AlF6 cryolite, followed by electrolysis using graphite electrodes. This method of obtaining requires large amounts of electricity, and therefore was in demand only in the 20th century.

Application

Aluminum is widely used as structural material. The main advantages of aluminum in this quality are lightness, ductility for stamping, corrosion resistance (in air, aluminum is instantly covered with a strong Al2O3 film, which prevents its further oxidation), high thermal conductivity, non-toxicity of its compounds. In particular, these properties have made aluminum extremely popular in the manufacture of cookware, aluminum foil in the food industry, and for packaging.

The main disadvantage of aluminum as a structural material is its low strength, so it is usually alloyed with a small amount of copper and magnesium (the alloy is called duralumin).

The electrical conductivity of aluminum is comparable to copper, while aluminum is cheaper. Therefore, it is widely used in electrical engineering for the manufacture of wires, their shielding, and even in microelectronics for the manufacture of conductors in chips. True, aluminum as an electrical material has an unpleasant property - because of the strong oxide film, it is difficult to solder it.

Due to the complex of properties, it is widely used in thermal equipment.

The introduction of aluminum alloys in construction reduces metal consumption, increases the durability and reliability of structures when operating them in extreme conditions (low temperature, earthquake, etc.).

Aluminum is widely used in various types of transport. At the present stage of aviation development, aluminum alloys are the main structural materials in aircraft construction. Aluminum and alloys based on it are increasingly used in shipbuilding. Hulls, deck superstructures, communications and various kinds of ship equipment are made from aluminum alloys.

Research is underway to develop foamed aluminum as a particularly strong and lightweight material.

precious aluminum

Aluminum is one of the most popular and widely used metals today. From the very moment of its discovery in the middle of the 19th century, it was considered one of the most valuable due to its amazing qualities: white as silver, light in weight and not affected by the environment. Its value was higher than the price of gold. Not surprisingly, aluminum was first used in the creation of jewelry and expensive decorative items.

In 1855, at the Universal Exhibition in Paris, aluminum was the main attraction. Aluminum items were placed in a showcase adjacent to French crown diamonds. Gradually, a certain fashion for aluminum was born. It was considered a noble, little-studied metal, used exclusively to create works of art.

Most often, aluminum was used by jewelers. With the help of a special surface treatment, jewelers achieved the lightest color of the metal, which is why it was often equated with silver. But compared to silver, aluminum had a softer luster, which made jewelers even more fond of it.

Because chemical and physical properties of aluminum at first they were poorly studied, jewelers themselves invented new techniques for processing it. Aluminum is technically easy to process, this soft metal allows you to create prints of any patterns, apply drawings and create the desired shape of the product. Aluminum was covered with gold, polished and brought to matte shades.

But over time, aluminum began to fall in price. If in 1854-1856 the cost of one kilogram of aluminum was 3 thousand old francs, then in the mid-1860s, about a hundred old francs were already given per kilogram of this metal. Subsequently, due to the low cost, aluminum fell out of fashion.

Currently, the very first aluminum products are very rare. Most of them did not survive the depreciation of the metal and were replaced by silver, gold and other precious metals and alloys. Recently, there has been renewed interest in aluminum among specialists. This metal was the subject of a separate exhibition organized in 2000 by the Carnegie Museum in Pittsburgh. Located in France Institute of Aluminum History, which in particular is engaged in the study of the first jewelry made from this metal.

In the Soviet Union, catering appliances, kettles, etc. were made from aluminum. And not only. The first Soviet satellite was made of aluminum alloy. Another consumer of aluminum is the electrical industry: wires of high-voltage transmission lines, windings of motors and transformers, cables, lamp bases, capacitors and many other products are made from it. In addition, aluminum powder is used in explosives and solid propellants for rockets, using its ability to quickly ignite: if aluminum was not covered with a thin oxide film, it could flare up in air.

The latest invention is aluminum foam, the so-called. "metal foam", which is predicted a great future.

[ abstract ]

Laboratory work - Cast alloys and melting [ laboratory work ]

Diagram aluminum-copper. Annealing. Iron carbide state diagram [document]

Presentation - Aluminum [ abstract ]

Structural steels and alloys [document]

Non-ferrous metals and alloys [lecture]

1.doc

FEDERAL RAILWAY TRANSPORT AGENCY

STATE EDUCATIONAL INSTITUTION

"Irkutsk State Transport University"

Essay

Subject:

"Aluminum and its alloys"

Introduction...............................................................................................................

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Each of these elements gives specific alloy properties; they are added only to the base aluminum, two-two, three-three. Aluminum alloys are grouped into "Series" according to their construction, as described below. Mechanical characteristics can be increased, within certain limits, by position.

Their corrosion resistance is less than that of other aluminum alloys; for this reason, in critical applications, they need protection systems; for the same reason thin basswoods are also available coated with other alloys with better corrosion resistance.

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Aluminum processing…………………………………………………………

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^ Aluminum alloys ………………………………………………………….

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Other alloying elements…………………………………………………

They are characterized by excellent machinability and limited weldability with the possibility of burning. This is the tightening of alloys; mechanical characteristics are usually inferior to those of commercial alloys. They have good melt weldability.

They have good formability, machinability, cleanliness and weldability. These are heat treatment alloys; after heat treatment, the highest mechanical characteristics among aluminum alloys develop. Alloys with the highest mechanical performance may have tensor susceptibility to corrosion; for this reason, specific "stabilized" treatment states have been developed.

^ The main natural compounds of aluminum ....................................................

Chemical properties…………………………………………………………..

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^ Application of aluminum ………………………………………………………

Conclusion………………………………………………………………………

Bibliography……………………………………………………………

They are used for aircraft structures and vehicles, and in general for heavily loaded parts. Aluminum pure industrial alloys. . Modern mechanical engineering requires steel with different properties. In one case, it must withstand high pressures, in others it does not react with acids and bases, thirdly, it is resistant to different temperatures, and so on. Therefore, the steel is alloyed with alloying additives or alloying elements such as tungsten, vanadium, chromium, manganese, nickel, titanium, silicon and others.

Introduction

Aluminum is a silvery-white metal with high electrical and thermal conductivity. It has a low density - approximately three times less than that of iron, copper and zinc. Therefore, the specific strength of this metal is high. The scope of application of aluminum and, in particular, its alloys is very wide. The latter now occupy the second place after iron-containing alloys. Therefore, the main part of the smelted aluminum is spent precisely on obtaining various alloys that have a wide variety of properties. A wide range of properties of aluminum alloys is due to the addition of various additives to the metal, which form solid solutions or intermetallic compounds (chemical compounds of metals) with it. Among aluminum alloys, the lion's share falls on such light alloys as duralumin and silumin. In metallurgy, aluminum is used not only as a base for alloys, but also widely used as alloying additions to copper and other metals.

Vanadium, for example, makes steel wear resistant and increases its strength. This is because oxygen and nitrogen dissolve into the molten metal during processing in a martin furnace, converter or electric furnace. When the metal is stuck in the mold, the gas starts to separate, but not all. Some of them are stuck in the metal and remain there in the form of bubbles. They reduce the strength of steel. Vanadium enters into a chemical reaction with gases, forming vanadium compounds that float on the surface of the molten metal and are separated from the slag.

^ Aluminum alloys are widely used in everyday life, in construction, architecture, automotive, shipbuilding, aviation, and space technology.

Particular mention should be made of semi-finished products and products made of aluminum, coated on the surface with a protective film of aluminum oxide, and products made of sintered aluminum alloys with an aluminum oxide frame. They have special physical, mechanical and even decorative properties. So, for example, various jewelry is made from aluminum coated with an electrochemically colored film, resembling gold in appearance.

In addition, vanadium lubricates steel crystals, which increases its strength. Tungsten also reduces steel crystals, but in addition to increasing strength, it also makes it fireproof. Chromium, combined with nickel, turns steel into a silicon-free, silk-free mattress, while manganese makes it hardwearing.

Often, several additives are added to steel. This gives it especially valuable and diverse properties. At present, refractory steels sometimes contain more than 10 alloying additions. As a rule, these additives are introduced into the metal not in pure form, but in the form of iron alloys. Steel, in which additives are introduced that give it special properties, is called alloy steel.

Aluminum - soft, light, silvery-white metal with high thermal and electrical conductivity. Melting point 660°C.

^ In terms of prevalence in the earth's crust, aluminum ranks 3rd after oxygen and silicon among all atoms and 1st among metals.

The advantages of aluminum and its alloys include its low density (2.7 g/cm3), relatively high strength characteristics, good thermal and electrical conductivity, manufacturability, and high corrosion resistance. The combination of these properties makes it possible to classify aluminum as one of the most important technical materials.

Alloys are compounds of two or more substances formed as a result of melt crystallization. They include both metals and non-metals: arsenic, carbon, silicon, and others. The properties of the alloy are fundamentally different from the properties of the constituent substances. It may have greater strength than its individual metal and may also have a different melting point. Most metal products are made from alloys.

Anyone who has seen pure iron, copper or tin knows that these are relatively soft metals. Even in ancient times, people noticed that a mixture of molten copper and tin forms a new substance called bronze. Bronze swords were harder than copper and iron, and also more reliable than flint blades. The process of mixing two metals was called an alloy, and the newly obtained mixtures of metals were called alloys, respectively. Alignment and alloying are inherently related processes, and sometimes we can talk about the same coincidence of the two concepts.

Aluminum and its alloys are divided according to the method of production into deformable, subjected to pressure treatment and foundry, used in the form of shaped casting; on the use of heat treatment - on thermally non-hardened and thermally hardened, as well as on systems doping.

^ state diagram

Again in antiquity blacksmiths noticed that forging hot iron became much stronger than bronze. The reason for this was that carbon had been added to the molten metal during the hardening process, which had been impregnated with a crystal lattice of iron. This led to a new alloy that we now know as steel. The amount of carbon in it determines its hardness and whether the resulting alloy will be steel or cast iron. If chromium is added to steel, it becomes stainless, tungsten makes it harder, and manganese makes it more resistant to wear.

equilibrium diagram, phase diagram - a graphic representation of the relationship between the state parameters of a physical and chemical system (temperature, pressure, etc.) and its composition. According to the state diagram, one can establish, for example, the temperatures of the beginning and end of phase transformations, the chemical composition of the phases. The state diagram is widely used in metal science.

Steel forging - hardening. Other alloys that are or are of value to humans are brass and duralumin. Iron alloys with nickel and chromium have a high electrical resistance, which makes them suitable for the production of heating elements.

They are heat resistant and acid resistant and are therefore widely used in industry. Nitinol is an alloy of nickel and titanium. It has a certain "memory" and, if subjected to deformation, after subsequent heating, the alloy will restore its original shape. Nitinol is an alloy that is particularly suitable for use in spacecraft and vehicles.

^ Classification of aluminum alloys

Depending on the method of production, industrial aluminum alloys are divided into sintered, cast and wrought (Fig. 1).

Cast alloys undergo eutectic transformation, while wrought alloys do not. The latter, in turn, are thermally non-hardened (alloys in which there are no phase transformations in the solid state) and deformable, thermally hardened (alloys hardened by quenching and aging).

The melting point of most alloys is lower than that of the lowest melting metal in the composition. This property can be useful, for example, an alloy of lead and tin used for soldering metals. The crystal lattices of alloys of liquid and solid-soluble metals are the three main types and are very similar to solid solutions, i.e. e. may not have a permanent composition. In the figure below, the first of the diagrams is a homogeneous crystalline metal grid of any metal. If metal alloys of two metals have atomic radii close in size, metal crystal lattices with substituted atoms can be formed.

^ Aluminum alloys are usually alloyed with Cu, Mg, Si, Mn, Zn, less often with Li, Ni, Ti.

Deformed aluminum alloys not hardened by heat treatment

This group of alloys includes commercial aluminum and non-hardened weldable corrosion-resistant alloys (alloys of aluminum with manganese and magnesium). AMts alloys belong to the Al - Mi system (Fig. 1).

These are, for example, alloys of gold - copper and gold - silver. When metal alloying with significant differences in the size of atomic radii forms a metal crystal lattice with "embedded" atoms. A mixed version is also possible when alloying three or more metals. In some cases, intermetallic compounds may be formed during the alloying process.

Various types of metal crystalline alloys. Crystalline alloys of alloys of metals that are soluble in the liquid but insoluble in the solid state are simply mechanical mixtures. For example, iron cannot form an alloy with lead or bismuth due to its different density. However, there is a possibility of mixing these metals by the powder metallurgist. This is a waste-free technology that creates complex shapes that are inaccessible to other technological methods.

^ Fig.1. State diagram "aluminum - alloying element":

1 - deformable, thermally non-hardening alloys;

2 - deformable, thermally hardened alloys.

^ Fig.2. State diagram “aluminum – manganese”:

Powder metallurgy of metal powder creates intricate parts. They are extremely accurate and do not need further processing. Their production process is characterized by economics and lack of protection, the latter also having an environmental benefit. Powder metallurgy parts can have a high degree of complexity, which can be difficult in classical methods such as forging, casting, stamping and pressing.

Metal powder can be produced through a number of methods, including chemical reactions, electrochemical methods, mechanical atomization, and melt atomization. In the case of mechanical atomization, metal powders can be obtained from waste metal chips and cuttings, which are crushed in mechanical mills or in apparatuses under the influence of powerful vortices. Melt spraying is applied to metals with a low melting point, which are melted into fine droplets in the molten state using compressed air.

–concentration of Mn in industrial alloys.

Fig.3. Microstructure of AMC alloy

^ Fig.6. Duralumin microstructure after:

a) quenching in water from temperature T2;

b) hardening and artificial aging at T3

Aluminum, beryllium or other elements such as phosphorus, aluminum, zinc, lead are added to the composition. The exception is copper alloy with zinc and copper-nickel alloys. Alloys, copper, no tin: one of the most popular is aluminum bronze, as well as honey permanent, but they are not related to bronze. Tin is the second component of the alloy, copper is the first. The third component can act: zinc, aluminum, arsenic and others. This alloy is the most used alloy. Humanity has been in it since ancient Egypt.

For a long time it was a strategically protective material. It was only a century before he made the instruments. It consists of tin and honey. This metal was one of the first absorbed by man. Compared with honey, it has more advantages such as hardness, technology, strength. The creation of bronze opened up many different possibilities for humanity that are still in use today.

(right - schematic)

The structure of the Amts alloy consists of an a-solid solution of manganese in aluminum and secondary precipitates of the MnAl phase (Fig. 3). In the presence of iron, instead of MnAl, a complex phase (MnFe) Al is formed, which is practically insoluble in aluminum, therefore the Amts alloy is strengthened by heat treatment.

^ The composition of these alloys has very narrow limits: 1-1.7% Mn;

Lead bronze is poorly worked by pressure, grinding or cutting. Lithuanian qualities are not inferior to other metals. This alloy has high corrosion resistance and anti-friction properties. It can be used for the mechanism of mechanical parts or in the chemical industry for the production of fittings. Lead, phosphorus can improve antifriction properties. The bronze bowl can also be alloyed with zinc, nickel, aluminum, arsenic. Adding up to eleven percent zinc does not change the characteristics of bronze, but is much cheaper.

0.05 - 0.20% Cu; copper is added to reduce pitting corrosion.

Allowed up to 0.6–0.7% Fe and. n 0.6-0.7% Si, which leads to some hardening of the alloys without a significant loss of corrosion resistance.

As the temperature decreases, the strength increases rapidly. Therefore, alloys of this group have found wide application in cryogenic technology.

The bronze alloy with zinc transplants is called "Admiralty", it is well protected from corrosion and sea water. We offer wholesale, bronze, brass, copper and non-ferrous alloys in bulk or deferred payments. Large selection of semi-finished products in stock. Always in the presence of copper and non-ferrous alloys, lead, admiralty, lead bronze, the prices are optimal from the seller. For wholesale buyers, the price is preferable. The warehouse has the largest selection of products for large-scale production. We also have attractive conditions for retailers.

AMg alloys (magnalium) belong to the A1 - Mg system (Fig. 4). Magnesium forms an a-solid solution with aluminum, and in the concentration range from 1.4 to 17.4% Mg, a secondary b-phase (MgAl) is released, but alloys containing up to 7% Mg give very little hardening during heat treatment, so they strengthened by plastic deformation-hardening.

Always available, brass, copper, bronze and rolled products, the price is due to the technological features of production, without taking into account additional costs. The price of the order depends on the volume and additional delivery conditions. Find us online. In this segment, Auremo is a profitable supplier. The quality complies with international standards. The best price from the seller. To get acquainted with the product catalog, check out our price list and get the information you need, you will be at the position of our website.

Designation and meaning of heat treatment

The online consultant is always at your disposal and will answer all your questions. We look forward to your orders - the company's Internet address in the contact section. Used for products that have been thermally hardened by low temperature heating after cold working. It is only suitable for alloys that have an aging process at normal temperature levels alloyed as they are hot worked.

Designation of heat treatment of rolled products

The group of non-ferrous metals includes copper, lead, zinc, tin, nickel, aluminum, and magnesium.

Alloys of A1–Mn systems. and A1–- Mg are used in the annealed, cold-worked and semi-hard-worked states. In industrial alloys, magnesium is contained in the range from 0.5 to 12 ... 13%, alloys with a low magnesium content have the best shaping ability, alloys with a high magnesium content have good casting properties (Table 5) applications.

^ Rescue boats, davits, outboard ladders, practical things, etc. are made on ships from alloys of this group.

Deformed aluminum alloys hardened by heat treatment

This group of alloys includes alloys of high and normal strength. The compositions of some wrought heat-hardenable alloys are given in Table 6 of the Appendix. Typical wrought aluminum alloys are duralumins (marked with the letter D) - alloys of the A1 - Cu - Mg system. In a very simplified way, the processes that take place during the hardening heat treatment of duralumin can be considered using the Al - Cu diagram (Fig. 5).

Fig.4. State diagram "aluminum - magnesium".

‚ – concentration of Mg in industrial alloys.

Fig.5. A fragment of the state diagram "aluminum - copper":

Т1 – melting temperature;

Т2 – hardening temperature;

T3 - artificial aging temperature.

Fig.7. State diagram "aluminum - silicon":

a) general view;

b) after the introduction of the modifier.

During quenching, which consists in heating the alloy above the line of variable solubility, holding at this temperature and rapid cooling, the structure of the supersaturated a - solid solution (light in Fig. 6a) and insoluble inclusions of ferruginous and manganese compounds (dark) is fixed. The alloy in the freshly quenched state has a low strength s6 = 30 kg/mm3 (300 MPa); d = 18%; hardness HB75.

A supersaturated solid solution is unstable. The highest strength is achieved with subsequent aging of the hardened alloy. Artificial aging consists in exposure at a temperature of 150 - 180 degrees. In this case, the strengthening phases CuAl2, CuMgAl2, Al12Mn2Cu are separated from the supersaturated a-solid solution.

^ The microstructure of the aged alloy is shown in Fig. 6b. It consists of a solid solution and inclusions of various phases listed above.

Aluminum processing

^ All aluminum alloys can be divided into two groups :

Wrought aluminum alloys - designed to produce semi-finished products (sheets, plates, rods, profiles, pipes, etc.), as well as forgings and die blanks by rolling, pressing, forging and stamping.

A) ^ Hardened by heat treatment:

Duralumins, "duralumin" (D1, D16, D20 *, aluminum alloys of copper and manganese) - are satisfactorily processed by cutting in the hardened and aged states, but poorly in the annealed state. Duralumins are well spot-welded and not fusion-welded due to their tendency to crack. Alloy D16 is used to manufacture skins, frames, stringers and spars of aircraft, load-bearing frames, building structures, and car bodies.

^ Avial Alloy (AB) satisfactorily processed by cutting after hardening and aging, well welded by argon-arc and contact welding. This alloy is used to manufacture various semi-finished products (sheets, profiles, pipes, etc.) used for structural elements bearing moderate loads, in addition, helicopter propeller blades, forged engine parts, frames, doors, which require high ductility in cold and hot condition.

^ High strength alloy (B95) has a tensile strength of 560-600 N / mm2, is well processed by cutting and welded by spot welding. The alloy is used in aircraft construction for loaded structures (skins, stringers, frames, spars) and for load-bearing frames in building structures.

^ Alloys for forging and stamping (AK6, AK8, AK4-1 [heat resistant]). Alloys of this type are distinguished by high ductility and satisfactory casting properties, which make it possible to obtain high-quality ingots. Aluminum alloys of this group are well processed by cutting and welded satisfactorily by contact and argon arc welding.

B ) Not hardened by heat treatment:

Alloys of aluminum with manganese (AMts) and aluminum with magnesium (AMg2, AMg3, AMg5, AMg6) are easily processed by pressure (stamping, bending), weld well and have good corrosion resistance. Cutting is difficult, therefore, to obtain a thread, special chipless taps (rollers) that do not have cutting edges are used.

Cast aluminum alloys - designed for shaped casting (as a rule, they are well processed by cutting).

^ Aluminum alloys with silicon (silumins) Al-Si (AL2, AL4, AL9) are distinguished by high casting properties, and castings - by high density. Silumins are relatively easy to machine.

^ Aluminum alloys with copper Al-Cu (AL7, AL19) after heat treatment, they have high mechanical properties at normal and elevated temperatures and are well processed by cutting.

^ Alloys of aluminum with magnesium Al-Mg (AL8, AL27 ) have good corrosion resistance, improved mechanical properties and are well processed by cutting. Alloys are used in shipbuilding and aviation.

^ Heat-resistant aluminum alloys (AL1, AL21, AL33) are well processed by cutting.

In terms of milling, threading and turning, aluminum alloys can also be divided into two groups. Depending on the state (hardened, aged, annealed), aluminum alloys can belong to different groups according to ease of processing:

Soft and ductile aluminum alloys that cause problems in machining:

a) Annealed: D16, AB.

b) Not hardened by heat treatment: AMts, AMg2, AMg3, AMg5, AMg6.

Relatively hard and strong aluminum alloys that are quite easy to machine (in many cases where increased productivity is not required, these materials can be machined with a standard tool for general use, but if you need to increase the speed and quality of processing, you need to use a specialized tool):

a) Hardened and artificially aged: D16T, D16N, AVT.

b) Forging: AK6, AK8, AK4-1.

c) Foundries: AL2, AL4, AL9, AL8, AL27, AL1, AL21, AL33.

Aluminum alloys and their applications

^ Aluminum is used for the production of products and alloys based on it.

alloying - the process of introducing additional elements into the melt that improve the mechanical, physical and chemical properties of the base material. Doping is a general concept of the series technological procedures carried out at various stages of obtaining a metallic material in order to improve the quality of metallurgical products.

^ The introduction of various alloying elements into aluminum significantly changes its properties, and sometimes gives it new specific properties.

The strength of pure aluminum does not satisfy modern industrial needs, therefore, for the manufacture of any products intended for industry, not pure aluminum is used, but its alloys.

With various alloying, strength, hardness increase, heat resistance and other properties are acquired. In this case, undesirable changes also occur: the electrical conductivity inevitably decreases, in many cases the corrosion resistance worsens, and the relative density almost always increases. The exception is alloying with manganese, which not only does not reduce corrosion resistance, but even slightly increases it, and magnesium, which also increases corrosion resistance (if it is not more than 3%) and reduces relative density, since it is lighter than aluminum.

^ Aluminum alloys

Aluminum alloys according to the method of manufacturing products from them are divided into two groups:

1) deformable (have high ductility when heated),

2) foundry (have good fluidity).

This division reflects the main technological properties of the alloys. To obtain these properties, different alloying elements are introduced into aluminum and in unequal amounts.

The raw materials for obtaining alloys of both types are not only commercially pure aluminum, but also aluminum-silicon binary alloys, which contain 10-13% Si, and differ slightly from each other in the amount of impurities of iron, calcium, titanium and manganese. The total content of impurities in them is 0.5-1.7%. These alloys are called silumins. In order to obtain wrought alloys, alloying elements soluble in it are mainly introduced into aluminum in an amount not exceeding the limit of their solubility at high temperature. Wrought alloys when heated under pressure treatment should have a homogeneous solid solution structure, providing the highest ductility and the lowest strength. This determines their good workability by pressure.

The main alloying elements in various wrought alloys are copper, magnesium, manganese and zinc, in addition, silicon, iron, nickel and some other elements are also introduced in relatively small quantities.

^ Duralumin - aluminum alloys with copper

Characteristic hardenable alloys are duralumin - alloys of aluminum with copper, which contain constant impurities of silicon and iron and can be alloyed with magnesium and manganese. The amount of copper in them is in the range of 2.2-7%.

^ Copper dissolves in aluminum in an amount of 0.5% at room temperature and 5.7% at a eutectic temperature of 548 C.

Heat treatment of duralumin consists of two stages. First, it is heated above the limiting solubility line (usually up to about 500 C). At this temperature, its structure is a homogeneous solid solution of copper in aluminum. By hardening, i.e. quick cooling in water, this structure is fixed at room temperature. In this case, the solution becomes supersaturated. In this state, i.e. in a state of hardening, duralumin is very soft and ductile.

The structure of hardened duralumin has little stability, and even at room temperature changes spontaneously occur in it. These changes come down to the fact that excess copper atoms are grouped in solution, arranged in an order close to that characteristic of crystals of the chemical compound CuAl. The chemical compound is not yet formed and, moreover, is not separated from the solid solution, but due to the uneven distribution of atoms in the crystal lattice of the solid solution, distortions occur in it, which lead to a significant increase in hardness and strength with a simultaneous decrease in the ductility of the alloy. The process of changing the structure of a hardened alloy at room temperature is called natural aging.

Natural aging occurs especially intensively during the first few hours, but it is completely completed, giving the alloy its maximum strength, after 4-6 days. If the alloy is heated to 100-150 C, then artificial aging will occur. In this case, the process is completed quickly, but the hardening occurs less. This is explained by the fact that at a higher temperature, the diffusion displacements of copper atoms are carried out more easily; therefore, the formation of the CuAl phase is completed and it is separated from the solid solution. The strengthening effect of the obtained phase turns out to be less than the effect of the distortion of the solid solution lattice that occurs during natural aging.

Comparison of the results of aging of duralumin at different temperatures shows that the maximum hardening is provided during natural aging within four days.

^ Alloys of aluminum with manganese and magnesium

Among non-hardenable aluminum alloys, alloys based on Al-Mn and Al-Mg have gained the most importance.

Manganese and magnesium, as well as copper, have a limited solubility in aluminum, which decreases with decreasing temperature. However, the effect of hardening during their heat treatment is small. This is explained as follows. In the process of crystallization in the manufacture of alloys containing up to 1.9% Mn, excess manganese liberated from the solid solution should have formed with aluminum a chemical compound Al (MnFe) soluble in it, which does not dissolve in aluminum. Consequently, subsequent heating above the limiting solubility line does not ensure the formation of a homogeneous solid solution, the alloy remains heterogeneous, consisting of a solid solution and Al (MnFe) particles, and this leads to the impossibility of hardening and subsequent aging.

^ In the case of the Al-Mg system the reason for the lack of hardening during heat treatment is different. With a magnesium content of up to 1.4%, there can be no hardening, since within these limits it dissolves in aluminum at room temperature and no precipitation of excess phases occurs. At a higher magnesium content, quenching followed by chemical aging leads to the release of an excess phase - the chemical compound MgAl.

However, the properties of this compound are such that the processes preceding its isolation, and then the resulting inclusions, do not cause a noticeable hardening effect. Despite this, the introduction of both manganese and magnesium in aluminum is beneficial. They increase its strength and corrosion resistance (with a magnesium content of not more than 3%). In addition, magnesium alloys are lighter than pure aluminum..

^ Other alloying elements

Also, to improve some of the characteristics of aluminum, the following are used as alloying elements:

Beryllium added to reduce oxidation at elevated temperatures. Small additions of beryllium (0.01-0.05%) are used in aluminum casting alloys to improve fluidity in the production of internal combustion engine parts (pistons and cylinder heads).

Bor injected to increase electrical conductivity and as a refining additive. Boron is introduced into aluminum alloys used in nuclear power engineering (except for reactor parts), because it absorbs neutrons, preventing the spread of radiation. Boron is introduced on average in the amount of 0.095-0.1%.

Bismuth. Low melting point metals such as bismuth, lead, tin, cadmium are added to aluminum alloys to improve machinability. These elements form soft fusible phases that contribute to chip breakage and cutter lubrication.

^ Gallium is added in the amount of 0.01 - 0.1% to alloys, from which sacrificial anodes are further made.

Iron. In small quantities (>0.04%), it is introduced during the production of wires to increase strength and improve creep characteristics. Iron also reduces sticking to the walls of molds when casting into a chill mold.

Indium. The addition of 0.05 - 0.2% strengthens aluminum alloys during aging, especially at low copper content. Indium additives are used in aluminium-cadmium bearing alloys.

^ Cadmium. Approximately 0.3% cadmium is added to increase the strength and improve the corrosion properties of the alloys.

Calcium gives plasticity. With a calcium content of 5%, the alloy has the effect of superplasticity.

Siliconis the most used additive in foundry alloys. In the amount of 0.5-4% reduces the tendency to cracking. The combination of silicon and magnesium makes it possible to heat seal the alloy.

^ Tin improves cutting performance.

Titanium. The main task of titanium in alloys is grain refinement in castings and ingots, which greatly increases the strength and uniformity of properties throughout the volume.

The main natural compounds of aluminum:

1. Nephelines - (Na, K) 2O AlO3 2Si2.

2. Cryolite - А1F3 3NaF

3. Bauxite - aluminum ore Al2O3 xH2O (usually found with impurities of silicon oxides SiO2, iron Fe2O3, calcium carbonate CaCO3).

4. Kaolin - A12O3 2SiO2 2H2O.

5. Alumina - a mixture of kaolins with sand SiO2, limestone CaCO3, magnesite MgCO3.

Chemical properties:

Aluminum has a high chemical activity (in the series of voltages of metals, it occupies a place between magnesium and zinc).

Aluminum is easily oxidized by atmospheric oxygen, being covered with a strong protective film of aluminum oxide Al2O3, which prevents further oxidation and interaction with other substances, which leads to its high corrosion resistance.

4Al 3O2 = 2Al2O3

If the aluminum oxide film is destroyed, then aluminum actively interacts with water at ordinary temperature:

2Al 6H2O \u003d 2Al (OH) 3 ZH2

1. Deprived of the oxide film, aluminum dissolves easily in:

- alkalis with the formation of aluminates

2Al 2NaOH 2H2O = 2NaAlO2 3H2

- dilute acids with evolution of hydrogen

2A1 6HC1 = 2AlCl3 ZH2

2A1 ZH2SO4 \u003d Al2 (S04) 3 3H2

- strongly diluted and concentrated nitric acid passivates aluminum, so aluminum containers are used for storage and transportation of nitric acid. But when heated, aluminum dissolves in nitric acid:

Al 6HNO3 (conc.) \u003d Al (NO3) 3 ZNO2 ZH2O

2. Aluminum interacts with:

- halogens

2Аl ЗВr2 = 2АlВr3

- at high temperatures with other non-metals (sulfur, nitrogen, carbon)

^ 2Al 3S \u003d Al2S3 (aluminum sulfide)

2Al N2 = 2AlN (aluminum nitride)

4Al 3C \u003d A14C3 (aluminum carbide)

The reactions proceed with the release of a large amount

heat. 3. Aluminum is characterized by aluminothermic reactions -

recovery of metals from their oxides with aluminum.

^ Aluminothermy is used to obtain rare metals that form a strong bond with oxygen: niobium Nb, tantalum Ta, molybdenum Mo, tungsten W, etc.

2Al 3W3 \u003d 3W A12O3

A mixture of fine Al powder and Fe3O4 magnetic iron ore is called thermite, which, when ignited, releases a large amount of heat, and the temperature of the mixture rises to 3500 ° C. This process is used in thermite welding.

8Al 3Fe3O4 = 9Fe 4Al2O3

Application of aluminum alloys

Most aluminum alloys have high corrosion resistance in the natural atmosphere, sea water, solutions of many salts and chemicals, and in most foods. The latter property, combined with the fact that aluminum does not destroy vitamins, allows it to be widely used in the manufacture of dishes. Aluminum alloy structures are often used in sea water. Aluminum is widely used in construction in the form of cladding panels, doors, window frames, and electrical cables. Aluminum alloys are not subject to severe corrosion for a long time in contact with concrete, mortar, plaster, especially if the structures are not frequently wet. Aluminum is also widely used in mechanical engineering, tk. has good physical qualities.

But the main industry, currently simply unthinkable without the use of aluminum, is, of course, aviation. It is in aviation that all the important characteristics of aluminum have been most fully used.

^ Application of aluminum

Aluminum is widely used as a structural material. The main advantages of aluminum in this quality are lightness, ductility for stamping, corrosion resistance (in air, aluminum is instantly covered with a strong Al2O3 film, which prevents its further oxidation), high thermal conductivity, non-toxicity of its compounds. In particular, these properties have made aluminum extremely popular in the manufacture of cookware, aluminum foil in the food industry, and for packaging.

The main disadvantage of aluminum as a structural material - low strength, so it is usually alloyed with a small amount of copper and magnesium (the alloy is called duralumin).

The electrical conductivity of aluminum is comparable to copper, while aluminum is cheaper. Therefore, it is widely used in electrical engineering for the manufacture of wires, their shielding, and even in microelectronics for the manufacture of conductors in chips. True, aluminum as an electrical material has an unpleasant property - because of the strong oxide film, it is difficult to solder it.

^ Due to the complex of properties, it is widely used in thermal equipment.

The introduction of aluminum alloys in construction reduces metal consumption, increases the durability and reliability of structures when operating them in extreme conditions (low temperature, earthquake, etc.).

Aluminum is widely used in various types of transport. At the present stage of aviation development, aluminum alloys are the main structural materials in aircraft construction. Aluminum and alloys based on it are increasingly used in shipbuilding. Ship hulls are made from aluminum alloys. deck superstructures, communications and various types of ship equipment. Research is underway to develop foamed aluminum as a particularly strong and lightweight material.

Conclusion

It is difficult to find an industry where aluminum or its alloys are used - from microelectronics to heavy metallurgy. Of all light metals, aluminum is characterized by the largest volume of production, ranking second in the world industry after the production of steel. This is due to good mechanical properties, lightness, low melting point, which facilitates processing, high external qualities, especially after special processing. Given the listed and many other physical and chemical properties of aluminum, its inexhaustible amount in the earth's crust, we can say that aluminum is one of the most promising materials of the future.

^ Bibliography

Tikhonov V.N. Analytical chemistry of aluminum. M., "Science", 1971

aluminum alloys. The use of aluminum alloys. Reference guide. Editorial Board I.V. Gorynin and others. Moscow "Metallurgy", 1978.

Aluminum. Properties and physical metallurgy. Directory. J.E. Hatch. Moscow, Metallurgy, 1989.

Aluminum. N.G. Klyuchnikov, A.F. Wells. Uchpedgiz, 1958.

Metal science and technology of metals. Ed. Yu.P. Solntseva,
M.: "Metallurgy", 1988, 512 p.

Yu.M. Lakhtin, V.P. Leontiev. Materials Science. M.: "Engineering", 1980, 493 p.

), which received industrial application, was developed in 1909 by A. Wilm (Germany). With the production of this A. s. linked initial. period of development of metal aircraft construction. In the RSFSR, in 1922, at a non-ferrous metal processing plant in the village of Kolchugino, Vladimir Region, industrial production of sheet and section products from domestic aluminum was begun. chain-aluminum (creators Yu. G. Muzalevsky and S. M. Voronov), which differed in composition from German duralumin. The big role played by A. s. in the aircraft industry, is determined by a successful combination of properties: low density (2500-2900 kg / m3), high strength (up to 500-600 MPa), corrosion resistance, manufacturability in casting, pressure treatment, welding and cutting. Due to the high specific strength since the 20s. 20th century A. s. are the most important structural material in aircraft construction.
The main alloying components of A. s. - magnesium, zinc, silicon. As a result of alloying aluminum with one, two or more elements from among those listed in various combinations, as well as small additions of one or more transition metals - manganese, chromium, titanium, zirconium, nickel, iron, vanadium - more than 150 A are obtained and used in industry. With. In the 70s. in the number of alloying components A. s. drinks also entered.
All A. s. usually divided into deformable, from which sheets, plates, profiles and other semi-finished products are made by lamellar deformation of a cast billet, and foundries, which are intended exclusively for shaped casting. From deformable And. alloys of the following systems are of greatest importance.
Aluminum - magnesium with the addition of manganese, titanium, zirconium (alloys AM-2, AM-5, AM-6; the figure in the brand shows the approximate magnesium content in percent). These alloys are not hardened by heat treatment; in the annealed state, they are characterized by moderate strength (up to 350 MPa for AM-6), high ductility, very high corrosion resistance, and good weldability. Widely used for critical welded structures.
Aluminum - copper - magnesium with manganese additives - duralumins (D1, D16, D18, V65, D19, V17, VAD1). hardened by heat treatment; are subjected, as a rule, to hardening and natural aging. They are characterized by a combination of high static strength (up to 450-500 MPa) at room and elevated (up to 150-175°C) temperatures, high fatigue strength and fracture toughness. This combination of properties determined the widespread use of these alloys, especially D16 and D16ch (pure iron and silicon impurities), in aircraft construction. The disadvantage is low corrosion resistance; products require careful protection against corrosion.
Aluminum - zinc - magnesium - copper with additions of manganese, chromium, zirconium. Subjected to hardening and artificial aging. Alloys have the highest A. with. strength (up to 700 MPa for V96Ts). However, with aging to maximum strength, the sensitivity of these diamonds increases. to corrosion cracking, plasticity and values ​​of structural strength characteristics are reduced. For these alloys, modes of softening aging (overaging) have been introduced, which provide a combination of sufficiently high strength (420–470 MPa for V93 and V95) with satisfactory values ​​of resistance to corrosion cracking and structural strength. The V95 alloy, especially its V95pch (increasing the purity of iron and silicon impurities), is one of the most important structural materials in aircraft construction.
Aluminum - magnesium - lithium with additions of manganese and zirconium. Subjected to hardening and artificial aging. A distinctive feature is the combination of sufficiently high strength (420-450 MPa) with the lowest strength for industrial A. s. density (2500 kg/m), high modulus of elasticity (75 GPa) and satisfactory weldability. Disadvantages: reduced ductility, poor processing properties.
Of the casting alloys, the alloys of the following systems are of greatest importance.
Aluminum - silicon, (silumins) with the addition of magnesium, copper, manganese, titanium, nickel (AL2, AL4, AL9, AL5, AL34) are the most common foundry aluminum alloys. In the presence of magnesium and copper alloys are hardened by heat treatment. Mechanical properties vary widely (strength from 15 MPa for AL2 to 350 MPa for AL34). The alloys are characterized by very good casting properties, satisfactory corrosion resistance and good weldability.
Aluminum - copper with additions of manganese, titanium, nickel, zirconium, cerium, cadmium (AL7, AL19, ALZZ, VAL10). They are hardened by hardening followed by artificial aging. This group includes the strongest (up to 500 MPa for VAL10) and the most heat-resistant (90 MPa for AL33) foundry A. with. Disadvantages: low corrosion resistance, reduced casting properties.
Along with deformable to foundry A. with. in the aircraft industry, sintered materials are used - sintered aluminum powder and sintered aluminum alloy.

Aviation: Encyclopedia. - M.: Great Russian Encyclopedia. Chief editor G.P. Svishchev. 1994 .

See what "Aluminum alloys" is in other dictionaries:

Alloys based on aluminum. The first A. s. received in the 50s. 19th century; they were an alloy of aluminum with silicon and were characterized by low strength and corrosion resistance. For a long time, Si was considered a harmful impurity in A. s. ... ... Great Soviet Encyclopedia

ALUMINUM ALLOYS- alloys based on aluminum with additions of Cu, Mg, Zn, Si, Mn, Li, Cd, Zr, Cr and other elements. Aluminum alloys have high electrical and thermal conductivity, good corrosion resistance. They are used in many branches of mechanical engineering. By… … Metallurgical Dictionary

They are widely used in military shipbuilding as materials, the use of which helps to lighten the weight of the ship's hull. AS are divided into cast and rolled. Cast A.S. represent an alloy of aluminum with copper (2 3%), ... ... Marine Dictionary

aluminum alloys- alloys based on aluminum (Al) with additions of Cu, Mg, Zn, Si, Mn, Li, Cd, Zr, Cr and other elements; characterized by low density (from 2.5 to 2.9 g / cm3), high specific strength with sufficiently satisfying plasticity, ... ... Encyclopedic Dictionary of Metallurgy

aluminum alloys Encyclopedia "Aviation"

aluminum alloys- aluminum alloys. First A. s. (duralumin), which received industrial application, was developed in 1909 by A. Wilm (Germany). With the production of this A. s. associated with the initial period of development of metal aircraft construction. In the RSFSR in 1922 at the plant ... ... Encyclopedia "Aviation"

Alloys based on aluminum with additions of copper, magnesium, zinc, silicon, manganese, lithium, cadmium, zirconium, chromium and other elements. A. s. have high mechanical with you and low density, high electrical and thermal conductivity, good corrosion. ... ... Big encyclopedic polytechnic dictionary

ALUMINUM ALLOYS- alloys with a tensile strength of 190 MPa or more, measured at a temperature of 293K (20C) ... Glossary of concepts and terms formulated in the normative documents of Russian legislation

When alloyed, aluminum combines with many metals; of the alloys obtained in this way, the alloy of copper with aluminum, aluminum bronze (see this next) deserves the most attention ... Encyclopedic Dictionary F.A. Brockhaus and I.A. Efron

sintered aluminum alloys (SAS)- high-strength materials obtained by sintering from alloyed Al powders or granules. In Russia, SAS with a high Si content (hypereutectic silumins) grades SAS 1 (25 30 ... Encyclopedic Dictionary of Metallurgy Read more

One of the most convenient materials in processing are metals. They also have their own leaders. For example, the basic properties of aluminum have been known to people for a long time. They are so suitable for use in everyday life that this metal has become very popular. What are the same as a simple substance and as an atom, we will consider in this article.

The history of the discovery of aluminum

From time immemorial, a person has known the compound of the metal in question - It was used as a means capable of swelling and binding the components of the mixture together, this was also necessary in the manufacture of leather products. The existence of pure aluminum oxide became known in the 18th century, in its second half. However, it was not received.

For the first time, the scientist H.K. Oersted managed to isolate the metal from its chloride. It was he who treated salt with potassium amalgam and isolated a gray powder from the mixture, which was aluminum in its pure form.

At the same time, it became clear that the chemical properties of aluminum are manifested in its high activity, strong reducing ability. Therefore, no one else worked with him for a long time.

However, in 1854, the Frenchman Deville was able to obtain metal ingots by melt electrolysis. This method is still relevant today. Particularly mass production of valuable material began in the 20th century, when the problems of obtaining a large amount of electricity at enterprises were solved.

To date, this metal is one of the most popular and used in the construction and household industries.

General characteristics of the aluminum atom

If we characterize the element under consideration by its position in the periodic system, then several points can be distinguished.

1. Ordinal number - 13.
2. It is located in the third small period, the third group, the main subgroup.
3. Atomic mass - 26.98.
4. The number of valence electrons is 3.
5. The configuration of the outer layer is expressed by the formula 3s 2 3p 1 .
6. The name of the element is aluminum.
7. strongly expressed.
8. It has no isotopes in nature, it exists only in one form, with a mass number of 27.
9. The chemical symbol is AL, read as "aluminum" in formulas.
10. The oxidation state is one, equal to +3.

The chemical properties of aluminum are fully confirmed by the electronic structure of its atom, because having a large atomic radius and low electron affinity, it is able to act as a strong reducing agent, like all active metals.

Aluminum as a simple substance: physical properties

If we talk about aluminum, as a simple substance, then it is a silvery-white shiny metal. In air, it quickly oxidizes and becomes covered with a dense oxide film. The same thing happens with the action of concentrated acids.

The presence of such a feature makes products made of this metal resistant to corrosion, which, of course, is very convenient for people. Therefore, it is aluminum that finds such wide application in construction. also interesting in that this metal is very light, while durable and soft. The combination of such characteristics is not available to every substance.

There are several basic physical properties that are characteristic of aluminum.

1. High degree of malleability and plasticity. A light, strong and very thin foil is made from this metal, it is also rolled into a wire.
2. Melting point - 660 0 С.
3. Boiling point - 2450 0 С.
4. Density - 2.7 g / cm 3.
5. The crystal lattice is volumetric, face-centered, metallic.
6. Connection type - metal.

The physical and chemical properties of aluminum determine the areas of its application and use. If we talk about everyday aspects, then the characteristics already considered by us above play a big role. As a light, durable and anticorrosive metal, aluminum is used in aircraft and shipbuilding. Therefore, these properties are very important to know.

Chemical properties of aluminum

From the point of view of chemistry, the metal in question is a strong reducing agent that is capable of exhibiting high chemical activity, being a pure substance. The main thing is to eliminate the oxide film. In this case, the activity increases sharply.

The chemical properties of aluminum as a simple substance are determined by its ability to react with:

• acids;
• alkalis;
• halogens;
• gray.

It does not interact with water under normal conditions. At the same time, from halogens, without heating, it reacts only with iodine. Other reactions require temperature.

Examples can be given to illustrate the chemical properties of aluminum. Equations for interaction reactions with:

• acids- AL + HCL \u003d AlCL 3 + H 2;
• alkalis- 2Al + 6H 2 O + 2NaOH \u003d Na + 3H 2;
• halogens- AL + Hal = ALHal 3 ;
• gray- 2AL + 3S = AL 2 S 3 .

In general, the most important property of the substance under consideration is its high ability to restore other elements from their compounds.

Recovery ability

The reducing properties of aluminum are well traced in the reactions of interaction with oxides of other metals. It easily extracts them from the composition of the substance and allows them to exist in a simple form. For example: Cr 2 O 3 + AL = AL 2 O 3 + Cr.

In metallurgy, there is a whole technique for obtaining substances based on such reactions. It is called aluminothermy. Therefore, in the chemical industry, this element is used specifically for the production of other metals.

Distribution in nature

In terms of prevalence among other metal elements, aluminum ranks first. Its content in the earth's crust is 8.8%. If compared with non-metals, then its place will be third, after oxygen and silicon.

Due to its high chemical activity, it is not found in its pure form, but only in the composition of various compounds. So, for example, there are many ores, minerals, rocks, which include aluminum. However, it is mined only from bauxites, the content of which in nature is not too high.

The most common substances containing the metal in question are:

• feldspars;
• bauxite;
• granites;
• silica;
• aluminosilicates;
• basalts and others.

In a small amount, aluminum is necessarily part of the cells of living organisms. Some species of club mosses and marine life are able to accumulate this element inside their bodies throughout their lives.

Receipt

The physical and chemical properties of aluminum make it possible to obtain it in only one way: by electrolysis of a melt of the corresponding oxide. However, this process is technologically complex. The melting point of AL 2 O 3 exceeds 2000 0 C. Because of this, it cannot be directly subjected to electrolysis. Therefore, proceed as follows.

The product yield is 99.7%. However, it is possible to obtain an even purer metal, which is used for technical purposes.

Application

The mechanical properties of aluminum are not good enough to be used in its pure form. Therefore, alloys based on this substance are most often used. There are many of them, we can name the most basic ones.

1. Duralumin.
2. Aluminum-manganese.
3. Aluminum-magnesium.
4. Aluminium-copper.
5. Silumins.
6. Avial.

Their main difference is, of course, third-party additives. All of them are based on aluminum. Other metals make the material more durable, resistant to corrosion, wear-resistant and pliable in processing.

There are several main areas of application of aluminum both in pure form and in the form of its compounds (alloys).

Together with iron and its alloys, aluminum is the most important metal. It is these two representatives of the periodic system that have found the most extensive industrial application in the hands of man.

Properties of aluminum hydroxide

The hydroxide is the most common compound that forms aluminum. Its chemical properties are the same as those of the metal itself - it is amphoteric. This means that it is capable of manifesting a dual nature, reacting with both acids and alkalis.

Aluminum hydroxide itself is a white gelatinous precipitate. It is easy to obtain it by reacting an aluminum salt with an alkali or. When reacting with acids, this hydroxide gives the usual corresponding salt and water. If the reaction proceeds with alkali, then aluminum hydroxocomplexes are formed, in which its coordination number is 4. Example: Na is sodium tetrahydroxoaluminate.

Federal Agency for Education of the Russian Federation

State Technological University

"Moscow Institute of Steel and Alloys"

Russian School Olympiad

"Innovative technologies and materials science"

II stage: Scientific and creative competition

Direction (profile):

"Material science and technology of new materials"

"Properties of aluminum and applications in industry and everyday life"

I've done the work:

Zaitsev Viktor Vladislavovich

Moscow, 2009

1. Introduction

4. The use of aluminum and its alloys in industry and everyday life

4.1 Aviation

4.2 Shipbuilding

4.3 Rail transport

4.4 Road transport

4.5 Construction

4.6 Petroleum and chemical industry

4.7 Aluminum cookware

5. Conclusion

5.1. Aluminum is the material of the future

6. List of used literature

1. Introduction

In my essay on the topic “Properties of aluminum and applications in industry and everyday life”, I would like to point out the peculiarity of this metal and its superiority over others. My entire text is proof that aluminum is the metal of the future and without it our further development will be difficult.

1.1 General definition of aluminum

Aluminum ( lat. Aluminum, from alumen - alum) - a chemical element III gr. periodic system, atomic number 13, atomic mass 26.98154. Silver-white metal, light, ductile, with high electrical conductivity, tm = 660 °C. Chemically active (covered with a protective oxide film in air). In terms of prevalence in nature, it ranks 3rd among elements and 1st among metals (8.8% of the mass of the earth's crust). In terms of electrical conductivity, aluminum is in 4th place, second only to silver (it is in first place), copper and gold, which, given the low cost of aluminum, is of great practical importance. There is twice as much aluminum as iron and 350 times as much as copper, zinc, chromium, tin and lead combined. Its density is only 2.7 * 10 3 kg/m 3 . Aluminum has a face-centered cube lattice and is stable at temperatures from -269 °C to the melting point (660 °C). The thermal conductivity is at 24°C 2.37 W×cm -1 ×K -1 . The electrical resistance of high purity aluminum (99.99%) at 20°C is 2.6548×10 -8 Ohm×m, or 65% of the electrical resistance of the international standard of annealed copper. The reflectivity of the polished surface is over 90%.

1.2 History of aluminum production

The documented discovery of aluminum occurred in 1825. The Danish physicist Hans Christian Oersted first obtained this metal when he isolated it by the action of potassium amalgam on anhydrous aluminum chloride (obtained by passing chlorine through a hot mixture of aluminum oxide and coal). Having driven away the mercury, Oersted obtained aluminum, however, contaminated with impurities. In 1827, the German chemist Friedrich Wöhler obtained aluminum in powder form by reducing potassium hexafluoroaluminate. The modern method of producing aluminum was discovered in 1886 by a young American researcher, Charles Martin Hall. (From 1855 to 1890, only 200 tons of aluminum were obtained, and over the next decade, 28,000 tons of this metal were obtained worldwide using the Hall method.) Aluminum with a purity of over 99.99% was first obtained by electrolysis in 1920. In 1925, Edwards published some information about the physical and mechanical properties of such aluminum. In 1938 Taylor, Willey, Smith, and Edwards published an article that gives some of the properties of 99.996% pure aluminum, also obtained in France by electrolysis. The first edition of the monograph on the properties of aluminum was published in 1967. Until recently, it was believed that aluminum, as a very active metal, cannot occur in nature in a free state, but in 1978. in the rocks of the Siberian platform, native aluminum was found - in the form of whiskers only 0.5 mm long (with a thickness of threads of several micrometers). In the lunar soil, delivered to Earth from the regions of the Seas of Crises and Abundance, it was also possible to detect native aluminum. It is assumed that metallic aluminum can be formed by condensation from the gas. With a strong increase in temperature, aluminum halides decompose, passing into a state with a lower valency of the metal, for example, AlCl. When such a compound condenses with a decrease in temperature and the absence of oxygen, a disproportionation reaction occurs in the solid phase: some of the aluminum atoms are oxidized and go into the usual trivalent state, and some are reduced. Monovalent aluminum can be reduced only to the metal: 3AlCl > 2Al + AlCl 3 . This assumption is also supported by the filamentous shape of native aluminum crystals. Typically, crystals of this structure are formed due to rapid growth from the gas phase. Probably, microscopic aluminum nuggets in the lunar soil were formed in a similar way.

2. Classification of aluminum according to the degree of purity and its mechanical properties

In subsequent years, due to the relative ease of preparation and attractive properties, many works were published on the properties of aluminum. Pure aluminum has found wide application mainly in electronics - from electrolytic capacitors to the pinnacle of electronic engineering - microprocessors; in cryoelectronics, cryomagnetics. Newer methods for obtaining pure aluminum are the zone purification method, crystallization from amalgams (alloys of aluminum with mercury) and isolation from alkaline solutions. The degree of purity of aluminum is controlled by the value of electrical resistance at low temperatures. Currently, the following classification of aluminum according to the degree of purity is used:

Mechanical properties of aluminum at room temperature:

3. The main alloying elements in aluminum alloys and their functions

Pure aluminum is a rather soft metal - almost three times softer than copper, so even relatively thick aluminum plates and rods are easy to bend, but when aluminum forms alloys (there are a huge number of them), its hardness can increase tenfold. The most widely used:

Beryllium is added to reduce oxidation at elevated temperatures. Small additions of beryllium (0.01 - 0.05%) are used in aluminum casting alloys to improve fluidity in the production of internal combustion engine parts (pistons and cylinder heads).

Boron is introduced to increase electrical conductivity and as a refining additive. Boron is introduced into aluminum alloys used in nuclear energy (except for reactor parts), because it absorbs neutrons, preventing the spread of radiation. Boron is introduced on average in the amount of 0.095 - 0.1%.

Bismuth. Low melting point metals such as bismuth, lead, tin, cadmium are added to aluminum alloys to improve machinability. These elements form soft fusible phases that contribute to chip breakage and cutter lubrication.

Gallium is added in the amount of 0.01 - 0.1% to the alloys from which the sacrificial anodes are further made.

Iron. In small quantities (>0.04%) it is introduced during the production of wires to increase strength and improve creep characteristics. Iron also reduces sticking to the walls of molds when casting into a chill mold.

Indium. The addition of 0.05 - 0.2% strengthens aluminum alloys during aging, especially at low copper content. Indium additives are used in aluminum-cadmium bearing alloys.

Approximately 0.3% cadmium is added to increase the strength and improve the corrosion properties of the alloys.

Calcium gives plasticity. With a calcium content of 5%, the alloy has the effect of superplasticity.

Silicon is the most used additive in foundry alloys. In the amount of 0.5 - 4% reduces the tendency to cracking. The combination of silicon and magnesium makes it possible to heat seal the alloy.

Magnesium. The addition of magnesium significantly increases strength without reducing ductility, improves weldability and increases the corrosion resistance of the alloy.

Copper strengthens alloys, maximum hardening is achieved with a copper content of 4 - 6%. Alloys with copper are used in the production of pistons for internal combustion engines, high-quality cast parts for aircraft.

Tin improves machining.

Titanium. The main task of titanium in alloys is grain refinement in castings and ingots, which greatly increases the strength and uniformity of properties throughout the volume.

Aluminum is one of the most common and cheapest metals. Without it, it is difficult to imagine modern life. No wonder aluminum is called the metal of the 20th century. It lends itself well to processing: forging, stamping, rolling, drawing, pressing. Pure aluminum is a fairly soft metal; it is used to make electrical wires, structural parts, food foil, kitchen utensils and "silver" paint. This beautiful and light metal is widely used in construction and aviation technology. Aluminum reflects light very well. Therefore, it is used for the manufacture of mirrors - by metal deposition in a vacuum.