Axial ratio changes in H.C.P. ζ phases in the systems AuInCu and CuGeAu

Abstract

The lattice spacings of hexagonal close-packed ζ phase alloys of compositions falling along lines of constant electron concentration in the ternary systems AuInCu and CuGeAu have been determined accurately with an estimated precision of 1 in 15,000. It is found that the axial ratio remains constant with increasing gold or copper content along constant electron concentration lines for values greater than 1.36 in both AuInCu and CuGeAu alloys. These differing trends are discussed in terms of the possible electronic structures and in the light of previous studies of binary ζ phases. The decreasing trends in axial ratio are believed to be associated with the presence of Brillouin zone overlaps which occur in the higher ranges of electron concentration.