Vacancy concentrations in the martensite phases, ζ’2 and γ’2, of Au1-xCdx alloys (where x ranged from 0.475 to 0.500) were measured in samples which had been furnace-cooled or water-quenched from 763K. It was found that there was a tendency for xV to increase with composition. It exhibited a much higher concentration in water-quenched samples than in furnace-cooled samples; thus indicating the existence of a large number of quenched-in vacancies. Vacancy migration and long-range ordering during aging in the martensite and parent B2 phases of furnace-cooled and water-quenched samples with x = 0.495 and 0.475 were examined by measuring lattice constants and integrated intensities using the X-ray diffraction method. In both samples, martensite aging did not bring about any effective vacancy migration or detectable change in long-range order. In the B2 phase of water-quenched samples, the quenched-in vacancies were largely annealed-out by aging, which accompanied promotion of long-range order. The difference in ease of vacancy migration between martensite and parent phases was due to the difference in the crystal structure.

Vacancy Migration and Long-Range Ordering due to Aging in AuCd Shape Memory Alloys. H.Ishibashi, M.Kogachi, T.Ohba, X.Ren, K.Otsuka: Materials Science and Engineering A, 2002, 329-331, 568-72