Ordering of metal atoms in binary ccp, hcp, and bcc alloys

Abstract

Crystal structures of 27 ccp, 27 bcc, and 18 hcp orderedM _x N _y alloys with single coordinationT ^M _i of allM atoms and single coordinationT ^N _i of allN atoms were derived with the aid of a computer program. The coordination numbersT ^M _i ,T ^N _i ofM andN atoms and the maximum coordination numberT ^max _i are related byT ^N _i =T ^max _i −(T ^max _i −T ^M _i )x/y. Two types of special structures were found: homometric structures with identical coordination numbers and structures with identical short range order parameters. Comparison with structures obtained by the Ising model shows e.g., that different homometric structures or closely related structures can be obtained for identical interaction constants.