Page 23 - Curriculum Visions Dynamic Book

alloy: a mixture of a metal and various other elements.
corrosion: the slow decay of a substance resulting from contact with gases and liquids in the environment. The term
is often applied to metals. Rust is the corrosion of iron.
 Aluminium alloys are commonly used for racing bicycles to give strength and light weight.
 Wind turbines, such as those shown below, are often made with aluminium alloys so that the blade weight is kept to a minimum.
In exposed locations, resistance to corrosion is also vital.
 Aluminium is often found in electric motors. It is also widely used for the pistons in engines.
Special alloys
Aluminium alloys can be made as strong as steel. To make duralumin, which is both hard and strong, an alloy containing 4.5% copper, 0.6% manganese, and 1.5% magnesium
is heated to about 495°C and then dipped in cold water. It is then left to “age”over the next few days, during which time it beomes extremely hard.
To make alclad, an alloy that has
a soft aluminium centre and a hard, corrosion-resistant skin, an alloy
of magnesium, zinc, copper, and chromium is heat-treated, quenched and allowed to“age”. It is an ideal material for use on aircraft fuselages.
Where the aluminium alloy needs to retain strength at very high temperatures, nickel is alloyed with aluminium.
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