MICROSTRUCTURAL AND MECHANICAL PROPERTY CHARACTERISTICS OF BINARY NI-GE ALLOYS

Polycrystalline Ni3Ge intermetallic compound displays very poor ductil ity due to its weak grain boundary cohesion. In addition, its ductilit y cannot be improved by the boron doping method although this techniqu e has proved quite effective in a similar Ni3Al intermetallic compound . Therefore, dual phase method seems to be a reasonable choice for dev eloping advanced Ni-Ge based high temperature materials with a potenti al for industrial applications. In this communication, the recent prog ress in the microstructural and mechanical property characterization o f binary Ni-Ge alloys has been reviewed. In addition to the rapid prec ipitation of fine Ni3Ge particles in the Mi solid solution, the spinod al decomposition has been observed to occur in the initial stage of ag ing at 873 K, while vacancy-induced short range ordered structure was found in the naturally aged alloys. The elastic constants of Ni3Ge sin gle crystal at various annealing temperatures have been also determine d.