METAL ALLOYS: TYPES, PROPERTIES AND EXAMPLES - CHEMISTRY - 2024

The metal alloys are materials formed by combinations of two or more metals, or metals and non-metals. So these substances can be represented by the union of a primary metal (or base) and the name of this metal can come to represent the name of the alloy.

The alloy is created by a process of joining the different molten elements, in which the other elements are joined or dissolved in the base metal, joining the components to form a new material with mixed properties of each element separately.

This type of material is usually created to take advantage of the strengths of a metal and, simultaneously, combat its weaknesses through its union with another element that can meet these needs.

This occurs in examples such as steel, which uses carbon to strengthen the crystalline structure of iron; or in the case of bronze, which is recorded as the first alloy obtained by man and which has been used since the beginning of humanity.

Types

When talking about the types of metal alloys, beyond the elements that compose them, they must be studied under an electron microscope to differentiate according to their crystalline structure.

Thus, there are two types of metal alloys, according to their crystalline structure and the mechanism that was carried out for their formation: substitution alloys and interstitials.

Substitution alloys

These alloys are those in which the atoms of the alloying agent (the substance that binds to the base metal) replace atoms of the primary metal for the formation of the alloy.

This type of alloy is generated when the atoms of the base metal and those of the alloying agent are of similar size. Substitution alloys have the characteristic of having their constituent elements relatively close in the periodic table.

Brass is an example of a substitution alloy, which is formed by the union of copper and zinc. In turn, these have atoms of similar sizes and closeness in the periodic table.

Interstitial alloys

When the alloying agent or agents have atoms considerably smaller than those of the primary metal of the alloy, these can enter the crystalline structure of the second and filter between the larger atoms.

Steel is an example of an interstitial alloy, in which a smaller number of carbon atoms are located between the atoms in the crystal lattice of iron.

Properties

Contrary to many other materials, metallic alloys do not have a series of properties inherent to this type of mixture; These are usually formed to capture the desirable characteristics of each element and enhance its usefulness.

For this reason, these substances have a unique character when it comes to measuring their general properties, but they are known to be created to improve the following characteristics:

Resistance to deformation or impacts

The mechanical resistance of a metal can be increased by its union with another metallic or non-metallic element, as in the case of stainless steels.

They use chromium, nickel and iron to form a high tensile strength material for a wide spectrum of commercial and industrial uses.

In this way, aluminum alloys (with copper, zinc, magnesium or other metals) are another type of alloys in which the second components are added to improve the resistance of aluminum, a naturally soft pure metal.

Melting point

The melting point of alloys is different from that of pure metals: these materials do not have a fixed value, but rather they melt within a temperature range in which the substance becomes a mixture of liquid and solid phases.

The temperature at which melting begins is called solidus, and the temperature at which it ends is called liquidus.

Resistance to corrosion

Alloys can be formed for the purpose of enhancing a metal's ability to resist corrosion; in the case of zinc, it has a property of high resistance to the corrosion process, which makes it useful when mixing it with other metals such as copper and steel.

Appearance and color

There are alloys that have been created to beautify a metal and give it decorative uses. Alpaca (or new silver) is a material made of zinc, copper and nickel, which has a color and shine similar to silver that can confuse people who are not familiar with this material. Furthermore, it is used for numerous applications.

Heat conduction

Heat conduction can be decreased or increased with the union between a metal and another element.

In the case of brass, it is a very good conductor of heat and is useful for the production of domestic radiators and heat exchangers in industry. Also, copper alloys have lower heat conductivity than pure metal.

Electrical conduction

Electrical conduction can also be enhanced or impaired by the bonding of a metal to another substance.

Copper is naturally one of the best electrically conductive materials, but it will suffer in this regard by combining with other substances to form alloys.

Examples

Meteoric iron

It is that alloy that occurs naturally, obtained from meteorites characterized by their composition of nickel and iron, which fell to Earth in the past and allowed the first humans to use this material to forge weapons and tools.

Bronze

It represents the alloy of copper and tin, and it represented the basic alloy for making weapons, utensils, sculptures and jewelry during early times of mankind.

Brass

An alloy of copper and zinc. This material is used for its low friction to form part of locks, doorknobs and valves.

Manganese

This element is not found in free form in nature. It is commonly an alloying agent for iron in multiple mineral forms and may have important uses in stainless steels.

References

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5. Wright, A. (nd). Metal Alloys. Retrieved from azom.com