Properties & Uses of Alloys
What is an alloy?
- An alloy is a mixture of two or more metals or metal with a non-metal such as carbon
- Steel is made from iron and carbon
- Alloys often have properties that can be very different from the metals they contain
- They can be stronger and harder
- They are resistance to corrosion or extreme temperatures
- These enhanced properties can make alloys more useful than pure metals
Structure of an alloy
The regular arrangement of a metal lattice structure is distorted in alloys
Common alloys and their uses
- Brass is an alloy of copper and zinc and is much stronger than either metal
- It is used in musical instruments, ornaments and door knobs
- Different types of steel are made by varying the carbon content and by adding other metals
- For example Stainless steel is a mixture of iron and other elements, for example, chromium, nickel and carbon
- It is used in cutlery because of its hardness and resistance to corrosion
- Alloys of iron with tungsten are extremely hard and resistant to high temperatures
- Alloys of iron mixed with chromium or nickel are resistant to corrosion
- Aluminium is mixed with copper, manganese and silicon for aircraft body production as the alloy is stronger but still has a low density
Why are the properties of an alloy different to a pure metal?
- Alloys contain atoms of different sizes, which distorts the normally regular arrangements of atoms in metals
- This makes it more difficult for the layers to slide over each other, so alloys are usually much harder than the pure metal
Examiner Tip
Alloys are mixtures of substances, they are not chemically combined and an alloy is not a compound.
You are not expected to know the specific types of steel and their names.
