Ordering Process and Age-hardening Mechanism of CuPd-AuCu Pseudo-binary Alloys

Abstract

Ordering process and age-hardening mechanism of CuPd-AuCu pseudo-binary alloys were examined. In alloys with electron-atom ratios (e/a)<0.87, short range ordering was observed in the early stage of aging, thereafter, long range ordering occurred from grain boundaries by heterogeneous ordering mechanism. Age-hardening of these alloys was attained by the increase in volume fractions of CuPd and/or AuCuI phases. On the other hand, in alloys with e/a>0.87, fine domains of AuCuI type superlattice were formed very rapidly in the grain interior. The elastic strain field generated by this reaction caused age-hardening.