An alloy is a homogeneous mixture of one metal with one or more other metals or non-metals. An alloy is prepared by mixing metals in the molten state in a fixed proportion by weight. Various properties of metals like malleability, ductility, strength, hardness, resistance to corrosion and appearance etc. are improved by alloying of metals. For example,
Copper + Zinc = Brass
Iron + Carbon = Steel
Copper + Tin = Bronze
We shall now discuss various alloys formed by different metals.
1. Alloys of Aluminium
From aluminium following alloys are prepared:
Duralumin
It is also known as duralium. It consists of aluminium, copper, magnesium, and manganese. It is light, strong and resistant to corrosion.
Uses of Duralumin
- Duralumin is used for making aircraft bodies and parts, space satellites and pressure cookers.
- Duralumin is resistant to water corrosion, so it is used for making bodies of ships.
Magnelium
This alloy of aluminium consists of aluminium and magnesium. It is very light and hard.
Use of Magnelium: It is used to make light instruments and balance beams.
Alnico
It is made up of aluminium, nickel, cobalt and iron.
Use of Alnico: Alnico is used for making magnets.
2. Alloys of Iron
Iron is used to prepare two alloys called steel and stainless steel.
Steel
Steel is a very important alloy of iron which contains 0.1 % to 1.5% carbon. The main properties of steel are that it is hard, tough and strong.
Uses of Steel
1. It is used in construction of buildings and bridges.
2. It is also used to make nails, screws, railway lines and girders.
Stainless Steel
Stainless steel is also an alloy of iron which contains about 18% of chromium and nickel. Stainless steel is very hard and resistant to corrosion.
Uses of Stainless Steel
- Stainless steel is used for making knives, tools, cooking utensils and ornamental pieces because it is corrosion resistant.
- It is also used for making surgical instruments such as scissors and various equipments for industrial processes.
3. Alloys of Copper
The important alloys of copper are:
Brass
Brass is prepared by mixing zinc in copper. The main properties of brass are that it is malleable, strong, resistant to corrosion and can be easily cast in different shapes and sizes.
Uses of Brass
- Brass is used mainly for making cooking utensils, screws, nuts, bolts and scientific instruments.
- Brass is also used for making flower vases and fancy lamps.
Bronze
This alloy is prepared by mixing tin in copper. It is very strong and resistant to corrosion.
Uses of Bronze: Bronze is used for making statues, medals, cooking utensils and coins.
German Silver
This alloy of copper is prepared by mixing zinc and nickel in copper.
Uses of German Silver: It is used for making utensils, silver ware and for electroplating.
Alloy of Mercury
An alloy of mercury metal with one or more other metal is called as an amalgam. For example sodium amalgam is prepared by mixing sodium metal in mercury.
Alloy of Lead
The most important alloy of lead is solder. It is prepared by mixing tin in lead.
Uses of Solder: It is used for joining metals and wires in electrical work.
Alloy of Gold
Pure gold is very soft due to which it is unsuitable to make jewelry. Purity of gold is measured in carats. Pure gold is of 24 carats. In order to make gold hard and fit for making jewelry copper or silver are mixed in it.
Test your understanding and answer these questions:
- What are alloys?