MICROSTRUCTURAL AND MECHANICAL PROPERTY CHARACTERISTICS OF BINARY Ni-Ge ALLOYS

Abstract

Polycrystalline Ni 3 Ge intermetallic compound displays very poor ductility due to its weak grain boundary cohesion. In addition, its ductility cannot be improved by the boron doping method although this technique has proved quite effective in a similar Ni 3 Al intermetallic compound. Therefore, dual phase method seems to be a reasonable choice for developing advanced Ni–Ge based high temperature materials with a potential for industrial applications. In this communication, the recent progress in the microstructural and mechanical property characterization of binary Ni–Ge alloys has been reviewed. In addition to the rapid precipitation of fine Ni3Ge particles in the Ni solid solution, the spinodal decomposition has been observed to occur in the initial stage of aging at 873 K, while vacancy-induced short range ordered structure was found in the naturally aged alloys. The elastic constants of Ni 3 Ge single crystal at various annealing temperatures have been also determined.