An
alloy is a mixture of
metals or a mixture of a metal and another
element. Alloys are defined by 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).