<P> An alloy is a mixture of metals or a mixture of a metal and another element . Alloys are defined by a metallic bonding character . An alloy may be a solid solution of metal elements (a single phase) or a mixture of metallic phases (two or more solutions). Intermetallic compounds are alloys with a defined stoichiometry and crystal structure . Zintl phases are also sometimes considered alloys depending on bond types (see also: Van Arkel - Ketelaar triangle for information on classifying bonding in binary compounds). </P> <P> Alloys are used in a wide variety of applications . In some cases, a combination of metals may reduce the overall cost of the material while preserving important properties . In other cases, the combination of metals imparts synergistic properties to the constituent metal elements such as corrosion resistance or mechanical strength . Examples of alloys are steel, solder, brass, pewter, duralumin, bronze and amalgams . </P> <P> The alloy constituents are usually measured by mass percentage for practical applications, and in atomic fraction (see Atomic_ratio) for basic science studies . Alloys are usually classified as substitutional or interstitial alloys, depending on the atomic arrangement that forms the alloy . They can be further classified as homogeneous (consisting of a single phase), or heterogeneous (consisting of two or more phases) or intermetallic . </P>

Why are alloys used more than pure metals
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