Alloys are homogeneous solid solutions in which the atoms of one metal are distributed randomly among the atoms of other metals to change its composition and strengthen its intrinsic properties., it may be the mixture of two or more types of metals, and sometimes non-metals can also be used in making alloys (in the case of stainless steel, <1.2% carbon atoms are used).
Formation of alloys
Alloys are generally formed by those atoms which have metallic radii within about 15% of each other.
Transition metals form a large number of alloys because these metals are quite similar in size and therefore the atoms of one metal can substitute the atoms of other metals in its crystal lattice.
Examples of alloy
- Alnico: Alnico is an alloy of Al + Ni + Co
- Brass: Brass is an alloy of Cu (60-80%) + Zn (20-40%)
- Bronze or Bell Metal: Bronze is an alloy of Cu (75-90%) + Sn (20-40%)
- Constantan: Constatan is an alloy of Ni + Cu
- Duralumin: Duralumin is an alloy of Cu + Al + Mn
- German Silver: German silver is an alloy of Cu + Ni + Zn in a ratio of 2:1:1
- Gun Metal: Gunmetal is an alloy of Cu + Sn + Zn in a ratio of 87:10:3
- Nichrome: Nichrome is an alloy of Ni + Cr + Fe
- Solder: Solder is an alloy of Sn + Pb
- 18 Carat Gold: 18 Carat gold is an alloy of Au + Ag + Cu
- 22 Carat Gold: 22 Carat gold is an alloy of Au + Ag
- Alloys of steel: It is made up of a combination of iron and at least one other element, such as carbon, manganese, chromium, vanadium, nickel, and molybdenum. The other elements are added to increase the strength, hardness, and other properties of the steel. These alloys are used in a variety of applications, such as automotive parts, aerospace components, and construction materials.
- Chromium Steel: Cr (2-4%)
- Invar: Ni (36%)
- Nickel Steel: Ni (3-5%)
- Stainless Steel: Cr + Fe + Ni + Carbon
Facts
- An alloy with mercury (Hg) is called amalgam.
- Iron (Fe), Cobalt (Co), and Nickel (Ni) do not form an amalgam with mercury (Hg) because of the large size difference with respect to mercury.
- The alloy of lanthanoid series elements with iron is called misch metal.
- Nickel (Ni) is used in the formation of alloys because of their shining properties.
- Chromium (Cr) is used in the formation of alloys because of its rust-resistant properties, it forms an oxide layer over the iron and protects them from rusting.
- Iron (Fe) and Carbon (C) is used in the formation of alloys to increase the hardness.
Uses
Alnico– It is used in making permanent magnets.
Duralumin– It is used in making aeroplane parts because of its lightweight property.
Solder– It is used in electrical industries for making electrical connections by the soldering process.