PHONON SOFTENING AND TIME-DEPENDENCE OF ELASTIC PEAK APPEARING PRIOR TO THE MARTENSITIC-TRANSFORMATION IN AU-47.5 AT-PERCENT-CD

There are two distinct martensites called gamma'(2) and zeta'(2) phase s near the equi-atomic composition in AuCd alloy system. The phonon di spersion relation of the [zeta zeta 0]TA(2) branch was measured by ine lastic neutron scattering in a AU(52.5)Cd(47.5) alloy which produces g amma'(2) martensite. The difficulty of strong neutron absorption was o vercome by the use of an isotope Cd-114. The softening was observed at the Brillouin zone boundary and at zeta = 0.35. An elastic peak was o bserved at zeta = 0.35, but not at the zone boundary. The peculiar tim e dependent behavior was observed in the elastic peak.