The homogeneous mixture of two or more metals, or a metal and a non-metal is called Alloy.
Types of alloys :
- Ferrous alloys: An alloy in which iron (Fe) is present. For example : manganese steel (Fe = 86% ; Mn = 13% ; C = 1%) and Nickel steel (Fe = 98% ; Ni = 2%).
- Non-ferrous alloys: An alloy does not contain iron. For example : Brass (Cu = 80% ; Zn = 20%), and Bronze (Cu = 90% ; Sn = 10%).
- Amalgams: An alloy in which mercury (Hg) is present. For example Sodium amalgams [Na(Hg)] and Zinc amalgams [Zn(Hg)].
Properties of an Alloy
- Alloys are stronger than the metal from which they are obtained.
- It is harder than the constituent metals.
- More resistance to corrosion.
- The melting point of alloys is lower than the constituent metals.Example: Solder [Sn(80%) + Pb(50%)] has lower m. p. than Pb and Sn.
- The electrical conductivity of alloys is lower than the constituent metals.
Some examples of Alloys:
- Brass: [80% Cu + 20% Zn ]
- Bronze: [88% Cu + 12% Sn]
- Solder: [50% Pb + 50% Sn]
- Duralumin: [95% Al + 4% Cu + 0.5% Mg + 0.5 Mn]
- Steel: [99.95% Fe + 0.05% C]
- Stainless steel: [74% Fe + 18% Cr + 8% Ni]
- German Silver: [60% Cu + 20% Zn + 20% Ni]
- Alloys of Gold: Pure gold is said to be of 24 carats. Gold is alloyed with a small amount of silver or copper to make it hard.
