The metallurgical industry plays an exceptional role in the national economy, the global economy and in the life of each particular person. Metal alloys are the key material for the creation of various devices and constructions. Alloys influenced the development of civilization as a whole; no wonder that there is a period of history that is called the Bronze Age. Some metals are extracted directly from ore, but the majority of them are made from various alloys. There are more than five thousand alloys today!
An alloy is a substance made by melting two or more metal elements, usually with the help of special additives. Bronze, which consists of copper (85%) and tin (15%), is deemed to be one of the first alloys. Nowadays one can call an alloy any substance which has one chemical element and a certain number of additives. Some metals are certainly recovered directly from ore or exist in nature in the so-called native state (platinum, gold, tin, quicksilver). But the majority of metals are obtained by working their compounds.
And in the modern industry metals are used exactly in the form of alloys obtained by adding other components to the main element. An interesting fact: cast iron and other steels are made from 90% of all iron recovered in the world.
In ancient times alloys were obtained by melting metals until their liquid state. According to historic records, ancient Indians also learnt how to make alloys with the help of high-melt zinc. The modern process of making alloys barely differs from the ancient one. We can single out several components in alloys:
— Base (the basic element; it can be one or several metal elements);
— Additives and alloying element;
— Residual impurities.
By production method alloys are divided into:
— Cast – obtained by crystallizing melt components;
— Powder – obtained by pressing a mixture of powders and fusing at a high temperature.
Alloy production methods are also divided into:
— cast (for instance, cast iron);
— deformable (steel likes of various types);
— powder (for instance, titanium, wolframium).
The most widespread types of alloys are iron-based ones. As we already noted, all iron is practically spent on the production of steels (plain and alloy) or cast iron. Such alloys can be obtained by adding carbon (0.25-4%) to iron. You need to add 2% of carbon to obtain various steels, while 2-4% of carbon is necessary for cast iron. It also includes silicon. If we speak about alloy steels (which are of higher quality), then nickel, chrome, vanadium and molybdenum are added to alloys. Nowadays high-alloy steels rich in chrome and nickel are actively used by the leaders of the fuel and energy complex for the offshore recovery of oil and gas.
If an alloy contains less than 0.25% of carbon, then it is used for technical constructions. If steel has more than 0.55% of carbon, it is perfect, for instance, for the production of various high-quality cutting tools: surgical supply cost, drills, cutters and so on. However details for quick cutting are made only from alloy steel. Cast iron is also used for a number of very tensile details, for instance, for engine blocks of cars. And cast iron was also used to found guns in the 14th century!
Alloys without iron are called non-ferrous (by analogy with the division of metals into ferrous and non-ferrous). The most used non-ferrous alloys are the ones based upon aluminum (titanium, magnesium, beryllium are also added) which are called high-tensile light alloys and have perfect mechanic characteristics. Coppers (brasses), which are made by adding a significant amount of zinc (up to 45%) are also widely used. One uses copper alloys with silicon, tin, beryllium, aluminum which are called bronzes. And finally, we should mention alloys on the basis of lead with an addition of tin, as well as arsenic, antimony, babbit and so on.
Light alloys from aluminum are deemed to be cost-effective and long term since they are not subject to corrosion, and no expensive equipment is necessary to mould them. Moreover, they are tensile and can withstand extra low temperatures. Aluminum alloys has good electrical and heat conductivity. Owing to their high technical characteristics, such aluminum alloys are used in various industries. For instance, they are actively used in the aviation, space, military, research and engineering and many other industries. Aluminum alloys are used for the production of pistons for internal combustion engines, engineering structures, bodies of various machinery, electrical wiring and so on.
In its turn, the military industry uses aluminum alloys for the production of light armor for machinery: it withstands impact loads and does not spark even upon abrupt mechanic impacts and effects. Furthermore, aluminum is used for the production of details for modern household appliances and mobile devices, aircrafts, aircraft equipment. An important moment: aluminum alloys are deemed to be absolutely harmless to human health and therefore can be used for the production of food crockery and cutlery.
Copper alloys are also very common; they are very tensile and, for instance, are used for the production of strings, membranes and so on. Lead alloys are presently used for the production of cables, bearings, safety locks since these alloys can withstand very high temperatures and complex natural conditions. Such peculiarities of lead alloys were known back in ancient times. For instance, ancient Romans constructed water lines from lead!
The key property of all alloys is weldability. As for other properties, they do not differ from metals. For instance, alloys are heat and electricity conducting and ductile.
An alloy’s ability to resist mechanic effects, loads
An alloy’s ability to resist the penetration of a detail made from metal or another alloy
An alloy’s ability to change its shape and size under mechanical loads
An alloy’s ability to resist rapidly increasing or extra high loads
An alloy’s ability to take the initial shape under mechanical loads
By alloying certain metals and other chemical elements, you can obtain materials with improved characteristics, for instance, with higher magnetic, thermal and/or electrical properties.
Let us say, if we alloy aluminum with copper, zinc and magnesium in a required ration, we can increase the fluidity of the first component by several times. Another example: alloys with magnesium are characterized by lightness (small mass) and high tenacity. In view of this, magnesium alloys are perfect for the foundry industry and actively used in the production of rockets, turbines, bodies and details which are used in extreme conditions, of car wheel disks and even armor steel. And if you add to magnesium a required amount of nickel, copper and chrome, submerging magnesium in pure zinc melt beforehand, you can significantly improve the properties of metal in terms of tenacity and resistance to abrasion.
In conclusion, alloy production is the foundation of practically all branches of economy, and, as a result, the life of all people. New methods of obtaining new high-quality alloys, new technologies of their making, as well as new ways of using them, are developed year after year. It is possible that in the future we will obtain miraculous compounds which will bring together all useful properties of metal components which can be used everywhere!