Alloy is a homogeneous composite material. Alloy properties

2024 Author: Howard Calhoun | [email protected]. Last modified: 2023-12-17 10:16

Everyone has heard the word "alloy", and some consider it synonymous with the term "metal". But these concepts are different. Metals are a group of characteristic chemical elements, while an alloy is a product of their combination. In its pure form, metals are practically not used, moreover, they are difficult to obtain in their pure form. Whereas alloys are ubiquitous.

What is alloy

Let's take a closer look at this issue. So, an alloy is a combination of several metals or one and various non-metallic additives. Such connections are used everywhere. An alloy is a macroscopic homogeneous system obtained by melting. They have been known since ancient times, when humanity, using primitive technologies, learned to produce cast iron, bronze, and a little later, steel.

The production and use of these materials is due to the fact that it is possible to obtain an alloy with desired technological properties, while many characteristics (strength, hardness, corrosion resistance, and others) are higher than those ofits individual components.

Main species

How are alloys classified? This is done according to the type of metal, which is the basis of the connection, namely:

1. Black. The base is iron. Ferrous alloys include all types of steels and cast irons.
2. Colored. The base is one of the non-ferrous metals. The most common non-ferrous alloys are based on copper and aluminum.
3. Rare metal alloys. Based on vanadium, niobium, tantalum, tungsten. Mainly used in electrical engineering.
4. Alloys of radioactive metals.

To the main component, other elements are added to the alloy - metals and non-metals, which improve its technological properties. These additives are called alloying. Also, harmful impurities are present in the alloys - if their permissible value is exceeded, many characteristics of the material are reduced. So, now you know what an alloy is.

Alloys are also classified into double, triple and others - according to the number of components. According to the homogeneity of the structure - into homogeneous and heterogeneous. By distinctive properties - fusible and refractory, high-strength, heat-resistant, anti-friction, corrosion-resistant and materials with special properties.

Mechanical properties

Mechanical properties of alloys determine the performance of the material when exposed to external forces. In order to find out the characteristics of the connection, the sample is subjected to various tests (stretch, scratch, load, press a metal ball or diamond cone into it, study undermicroscope) to determine strength, elasticity, plasticity.

Physical

The composition of an alloy determines its physical properties. These include specific gravity, electrical conductivity, melting point, specific heat capacity, coefficient of volumetric and linear expansion. Physical properties also include the magnetic properties of alloys. They are characterized by residual induction and magnetic permeability.

Chemical

What is the chemical properties of the alloy? These are characteristics that determine how the material reacts to the impact of various active, including aggressive agents. The chemical impact of the environment can be seen visually: iron is “eaten up” by rust, a green coating of oxides appears on bronze, steel dissolves in sulfuric acid.

In metallurgy and heavy engineering, many methods are used to combat the aggressive influence of the external environment: new, more resistant materials based on copper, titanium and nickel are being developed, alloys are covered with protective layers - varnishes, paints, oxide films, improve their structure. As a result of negative environmental factors, the industry annually suffers damage amounting to millions of tons of steel and cast iron.

Technological

Manufacturability - what is it? An alloy in industry is needed not by itself, any part is made from it. Consequently, the material will be heated, cut, deformed, heat treated and other manipulations will be carried out. Manufacturability is the ability of an alloy to be subjected to various methods of hot andcold working, such as melting, easy to spread and fill the mold, hot or cold deformation (forging, hot and cold stamping), welding, metal-cutting.

Technological properties can be divided into:

1. Foundry. They are characterized by fluidity - the ability to fill the mold for casting, shrinkage (percentage of volume loss after cooling, solidification) and segregation - a complex process in which an inhomogeneous structure of the material is formed in different parts of the casting.
2. Forgeability. This is the ability of an alloy to deform under shock loading and take the desired shape without loss of integrity. Some metals are malleable only when hot, others both cold and hot. For example, steel is forged in hot form. Alloys of aluminum and brass take the desired shape well at room temperature. Bronze does not lend itself well to impact deformation, while cast irons are not ductile and are destroyed under the influence of a hammer (with the exception of malleable cast iron).
3. Weldability. Low-carbon steel has good weldability, this characteristic is much worse for high-alloy steels and cast irons.