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Science

Metals and alloys

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Alloys

An alloy is a mixture of two elements, one of which is a metal. Alloys often have properties that are different to the metals they contain. This makes them more useful than the pure metals alone. For example, alloys are often harder than the metal they contain.

Alloys contain atoms of different sizes, which distorts the regular arrangements of atoms. This makes it more difficult for the layers to slide over each other, so alloys are harder than the pure metal.

atoms of differing sizes create an irregular arrangement

It is more difficult for layers of atoms to slide over each other in alloys

A summary of three common alloys, the metals they contain, and their typical uses

alloymain metal(s) in alloytypical use
amalgammercurydental fillings
brasscopper and zinchinges, electrical plugs
solderlead and tinjoining metals

Smart alloys - higher

Smart alloys have unusual properties. Nitinol is an alloy of nickel and titanium, and is known as a shape memory alloy. If nitinol is bent out of shape, it returns to its original shape when it is either heated or an electric current is passed through it. This property makes it useful for making spectacle frames - they return to their original shape if they are put in hot water after bending them.

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