Alloys (CIE IGCSE Chemistry)

• An alloy is a mixture of two or more metals or metal with a non-metal such as carbon
• Alloys often have properties that can be very different from the metals they contain, for example, they can have more strength, hardness or resistance to corrosion or extreme temperatures
• These enhanced properties can make alloys more useful than pure metals

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
• 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

EXTENDED

• 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