First and Second Order Phase Changes in Splat Cooled Au-Cd and Au-Zn Alloys

摘要

X-ray diffraction, transmission electron microscopy and selected area electron diffraction studies were performed on splat cooled equi-atomic Au-Cd and Au-Zn alloys. A vertical shock-tube apparatus is used for splat quenching samples from various temperatures. A substantial increase in superlattice line intensities were observed for both alloys after splat cooling. This result was tentatively interpreted in terms of the formation of preferential sublattice vacancies. A new morphology and crystal structure of the martensitic phase in splat cooled Au-Cd alloy were observed and a periodically faulted martensite like phase was observed in a splat cooled 50 at.% Au-Zn alloy. Also observed in the splat cooled Au-Zn alloy was a hitherto unreported modulated structure. (Author)