What is a alloy

An alloy is a metal made by melting two or more pure metals together in a very hot furnace and mixing them together. When they cool and harden, they form a new metal. This is an alloy. Other alloys are made by mixing a melted metal with small amounts of a chemical that is not a metal. There are so many alloys made by man today that it would take a very thick book to list all of them. Usually an alloy is better for some special use than a pure metal would be. One of the first alloys made by man was bronze, a mixture of copper and tin.

Thousands of years ago, long, before man discovered iron, bronze was used for knives, swords, shields, and tools. Ancient man had found that copper was too soft for knives and other cutting tools. Then he learned that by adding a little tin to copper he could make a metal that was harder than either tin or copper. Brass is another alloy made with copper. It is made by adding zinc to the copper and is much harder than either of these metals. There are many different kinds of brass, depending on how much zinc is added to the copper.

Some of the strangest alloys are amalgams, which are mixtures of mercury with other metals. These alloys are made without melting either metal. There is a separate article on AMALGAM. Steel is one of the most important alloys in common use. It is made by melting iron and adding small amounts of pure carbon while the iron is still a hot liquid. Carbon is not a metal. Coal and charcoal—wood that has been burned black—are examples of carbon. Pure iron is a fairly soft metal. With enough carbon added, it becomes very hard. Stainless steel is made by mixing two metals called chrome and nickel with the hot melted steel. These metals will not rust, and so the entire alloy will not rust. Very few pure metals are used by modern man.

Even the silver dimes, quarters, and half-dollars we use have a little copper added to them to make them harder. Pure silver is a very soft metal and would wear out very quickly. Not all alloys are intended to make a harder or stronger metal. Sometimes a softer metal is needed. Solder is an alloy of tin and lead. It is useful because it melts at a very low temperature. When a stick of solder is touched to a hot iron, the solder quickly melts and drips down where needed. It hardens almost immediately, and will plug up a hole, or join pieces of metal together.

Scientists called metallurgists work constantly to develop new and better alloys. Some of the best known have special "trade names" given to them by their inventors. Duralumin is one of these. It is an alloy of aluminum and it was invented because modern airplanes needed a metal that is both lighter and stronger than pure aluminum. Carboloy is another. It is a mixture of carbon with two metals called cobalt and tungsten, and it was made to be the hardest alloy known, so as to make tools that would cut even the toughest steel alloys. Read the separate articles on METALS and on the different metals such as IRON, COPPER, and so on. New alloys are being created all the time.