An alloy is a metallic mixture between two or more metals (Remember that a mixture consists of two substances not chemically joined, while compounds have their substances chemically joined), though one of those elements can occasionally be a non-metal. There are many alloys:
- Steel, which consists of Carbon and Iron
- Bronze, which is a mixture of Copper and Tin
- Brass, a mixture of Copper and Zinc
- Galinstan®, consisting of Gallium, Indium, and Tin
The elements used to make alloys have to be at a certain percentage for the alloy to be at desired performance. Alloys are very useful in everyday objects, due to them being malleable, having hard strength, resistant to corrosion (see below) and having good electrical conductivity. They are used in building aircraft, construction, and in the structure of coins.
Corrosion is a natural process, which converts a refined metal to a more chemically (but not physically) stable form, such as the metal's corresponding oxide, hydroxide, or sulfide. In other words, it is the gradual destruction of metals by chemical reactions with their environment. However, it can be prevented by techniques like plating and coating. The Golden Gate Bridge is coated to prevent corrosion.