What is Alloy? – Definition, Properties, Formation, Facts, Examples | A Revolution in The Metallic World

What is an Alloy?

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

  1. Alnico: Alnico is an alloy of Al + Ni + Co
  2. Brass: Brass is an alloy of Cu (60-80%) + Zn (20-40%)
  3. Bronze or Bell Metal: Bronze is an alloy of Cu (75-90%) + Sn (20-40%)
  4. Constantan: Constatan is an alloy of Ni + Cu
  5. Duralumin: Duralumin is an alloy of Cu + Al + Mn
  6. German Silver: German silver is an alloy of Cu + Ni + Zn in ratio of 2:1:1
  7. Gun Metal: Gun metal is an alloy of Cu + Sn + Zn in ratio of 87:10:3
  8. Nichrome: Nichrome is an alloy of Ni + Cr + Fe
  9. Solder: Solder is an alloy of Sn + Pb
  10. 18 Carat Gold: 18 Carat gold is an alloy of Au + Ag + Cu
  11. 22 Carat Gold: 22 Carat gold is an alloy of Au + Ag
  12. Alloys of steel:
    • Chromium Steel: Cr (2-4%)
    • Invar: Ni (36%)
    • Nickel Steel: Ni (3-5%)
    • Stainless Steel: Cr + Fe + Ni + Carbon

Alloy facts

  • Alloy with mercury (Hg) is called amalgam.
  • Iron (Fe), Cobalt (Co), and Nickel (Ni) do not form amalgum with mercury (Hg) because of large size difference with respect to mercury.
  • Alloy of lanthanoid series elements with iron called misch metal.
  • Nickel (Ni) used in formation of alloys beacuse of their shining properties.
  • Chromium (Cr) used in formation of alloys because of their rust resistant properties, it forms oxide layer over the iron and protects them from rusting.
  • Iron (Fe) and Carbon (C) used in formation of alloys to increase the hardness.

Uses of alloys

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.

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