Alloys

Alloys

1. An alloy is a Mixture of a Metal and Other Elements

   • Alloys can be a mixture of two or more different metals (like brass or bronze)
   • They can also be a mixture of a metal and a non-metal (like steel)
   • Alloys often have properties that are different from the metals they are made from- and these new properties often make the alloy more useful than the pure metal

2. Steel is an Alloy of Iron and Carbon

   • Steel is harder than Iron
   • Steel is also stronger than iron, as long as the amount of carbon does not get larger than about 1%.
   • Iron on its own will rust fairly quickly, but steel is much less likely to rust.
   • A lot of things are made from steel- girders, bridges, engine parts, cutlery, washing machines, saucepans, ships, drill bits, cars etc.

3. Brass, Bronze, Solder and Amalgam are also Alloys

   • Brass is an alloy of copper and zinc. most of the properties of brass are just a mixture of those of the copper and zinc, although brass is harder than either of them. Brass is used for making brass musical instruments (trumpets, trombones, French horns etc.). it is also used for fixtures and fittings such as screws, springs, doorknobs etc.
   • Bronze is an alloy of copper and tin. It's much harder and stronger than tin, and it's more resistant to corrossion than either copper or tin. Broze is used to make springs and motor bearings. It's also used to make bells, and it's used in sculpture.
   • Solder is usually an alloy of lead and tin. Unlike pure materials it doesn;t have a definite melting point, but gradually solidifies as it cools down. This is pretty useful if you want to solder things together.
   • An amalgam is an alloy containing mercury. A large-scale use of one kind of amalgam is in dentistry, for filling teeth.
     • Modern fillings tend to be made from tooth-coloured resin instead. This is partly because amalgam fillings are dark silvery in colour, and thereforemrather obvious in your mouth, and partly becasue people worry that the mercury in the amlgam could cause health problems (although there is not much evidence for this).

4. Some Alloys are Smart

   • Nitinol is the name given to a family of alloys of nickel and titanium that have shape memory.
   • This means they "remember" their original shape, and go back to it even after being bent and twisted.
   • This has increased the number of uses for alloys. You can get specs with Nitinol frames- these can be bent and even sat on and they still go back into their original shape.