Synthesis of Nb-Mo-Si based in situ composite powder by a hydrogenation-dehydrogenation reaction

Nb-Mo-Si based in situ composite powders were fabricated by a hydrogenation-dehydrogenation reaction. The Nb-6Mo-20Si-3Cr alloy ingot was prepared by vacuum arc melting and was composed of a metal solid solution phase and a (Nb, Mo)5Si3 silicide phase. For hydrogenation, the ingot was annealed under a hydrogen atmosphere and the hydrogenated ingot could be easily pulverized by milling due to its brittle nature. As a result of absorbing hydrogen, the hydrogenated powder had a higher hydrogen concentration and lattice parameter than the ingot. The powder was annealed under a vacuum atmosphere for dehydrogenation and the hydrogen concentration and lattice parameter decreased to the same value as those of the ingot. By applying the hydrogenation-dehydrogenation method, Nb-6Mo-20Si-3Cr alloy powder could be successfully fabricated.