Preparation of ODS cobalt base superalloy by mechanical alloying and spark plasma sintering

摘要

ODS cobalt base superalloys with Y2O3 (mass fraction 2.0%) as dispersion phase were prepared by mechanical alloying and spark plasma sintering. The results show that when milling below 8h, the particle sizes and grain sizes of powders decrease remarkably with increasing the milling time, but when milling beyond 8h, the refinement of powders become very slowly. The sintered compacts with a relative density over 99% and an average grain size below 5μm can be obtained by spark plasma sintering at 1100°C from powders milled for 20h. After heat treatment at 1300°C, the compression strength and elongation of ODS cobalt base superalloys are 1982MPa and 23% respectively, much higher than those of cast cobalt base superalloy GH605.