Ordering process and age-hardening mechanism of CuPd-AuCu pseudo-binary alloys.

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 mecha nism. 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 superlatti were formed very rapidly in the grain interior. The elastic strain field generated by this reaction caus age-hardenin