Alloys and their properties
Alloys
- An alloy is a mixture of a metal with one or more other elements.
- Brass = copper + zinc.
- Stainless steel = iron + chromium, nickel, carbon.
- Alloys are usually harder and stronger than the pure metals, so they are more useful.
Practice
Brass is an alloy of:
Brass = copper + zinc; stainless steel = iron with chromium, nickel and carbon.
Practice
An alloy is a mixture of a metal with one or more other elements.
Alloys are mixtures, not compounds — the components are not chemically bonded.
Why alloys are harder
- In a pure metal, all atoms are the same size, so the layers slide easily.
- In an alloy, the different-sized atoms stop the layers sliding, so it is harder and stronger.
Practice
Why is an alloy harder than the pure metal?
The different-sized atoms disrupt the regular layers, so they cannot slide as easily — the alloy is harder.
You've got it
Key idea
- an alloy = a metal mixed with other elements (brass = Cu + Zn; stainless steel = Fe + Cr/Ni/C)
- alloys are harder and stronger than pure metals
- because different-sized atoms stop the layers sliding