There are many types of copper alloys with important uses. Brass is a copper-zinc alloy. Bronze usually refers to copper-tin alloys, but may also refer to other copper alloys such as aluminum bronze. In the jewelry industry, copper is an important component of alloys such as carat gold and carat silver, and is also used as a solder for carat gold, changing the color, hardness, and melting point of the alloy.
An alloy of copper and nickel known as white copper is used for small-denomination coins and is often used as a cladding. 5-cent coins contain 75% copper, 25% nickel, and are homogeneous. 90% copper and 10% nickel alloys have excellent corrosion resistance and are used in a variety of parts parts that come into contact with seawater. Copper-aluminum alloys (about 7% aluminum) are gold in color and are used for decorative purposes and are pleasing to the eye.Some lead-free alloys contain no lead. Some lead-free solders are alloys of tin and a small percentage of other metals such as copper.
