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Uses of alloys

have different properties to the pure metal. For any particular use, an alloy is matched that has the most suitable range of properties.

Aluminium and copper are useful . This table shows examples of common alloys that contain these metals:

AlloyCompositionUses
DuraluminAluminium and copperAircraft parts
MagnaliumAluminium and magnesiumAircraft parts
BronzeCopper and tinPropellers for ships, bells
BrassCopper and zincCoins, musical instruments
Jewellery goldGold and copperJewellery
SolderTin and copperJoining copper pipes and electrical components
AlloyDuralumin
CompositionAluminium and copper
UsesAircraft parts
AlloyMagnalium
CompositionAluminium and magnesium
UsesAircraft parts
AlloyBronze
CompositionCopper and tin
UsesPropellers for ships, bells
AlloyBrass
CompositionCopper and zinc
UsesCoins, musical instruments
AlloyJewellery gold
CompositionGold and copper
UsesJewellery
AlloySolder
CompositionTin and copper
UsesJoining copper pipes and electrical components

The uses of metals are related to their .

Aluminium and its alloys

Aluminium does not react with water. Its surface is protected by a natural layer of aluminium oxide that allows the metal to resist . Aluminium foil is used for wrapping and storing food because it does not react to substances in food. It is , so it is easily folded into shape around the food.

Aluminium has a low , so pieces of aluminium are relatively lightweight.

The alloys duralumin and magnalium are stronger than aluminium alone but still have low densities. They are used to make aircraft parts.

Question

Suggest an explanation for why magnalium is used to make aircraft parts.

Copper and brass

Copper and brass resist corrosion and are good electrical conductors. Copper is a better conductor than brass so it is used in electrical wiring. Brass is stronger than copper.

Electrical wires
Image caption,
Electrical wires are protected by tough layer of an insulating polymer

Question

Suggest why brass, not copper, is used for the pins on electrical plugs.

Gold

Gold is a very soft and malleable metal. It is also very so it resists corrosion and stays shiny. The visors on space helmets are coated with a layer of gold. This is thin enough for the astronaut to see through but thick enough to reflect sunlight. The gold used for jewellery is gold alloyed with other metals, often copper. This makes the jewellery much stronger while keeping its ability to stay shiny.