what is alloy

An alloy is a mixture of chemical elements, of which at least one is a metal. Unlike chemical compounds with metallic bases, an alloy will retain all the properties of a metal in the resulting material. Alloys are made by mixing two or more elements, at least one of which is a metal, and alloying elements are added to a base metal to induce hardness, toughness, ductility, or other desired properties. The added elements are well controlled to produce desirable properties, while impure metals such as wrought iron are less controlled but are often considered useful. The physical properties of an alloy, such as conductivity, reactivity, and density, may not differ significantly from its constituent elements. However, the engineering properties of an alloy, such as shear strength and tensile strength, may be substantially different. Alloys have a wide range of special properties, such as hardness, toughness, corrosion resistance, magnetizability, and ductility. Some alloys will take the best attributes of each contributing element and create a final product that is harder, more durable, and/or more resistant to corrosion. Alloys are usually produced by melting the mixture of ingredients. The most important alloys are the alloy steels, which contain significant amounts of elements other than iron and carbon. Nonferrous alloys, mainly copper–nickel, bronze, and aluminum alloys, are much used in coinage.