Fabrication of Mo-Si-B intermetallic powder by mechano-chemical process

Abstract

Mo-Si-B alloys have attracted attention as alternatives to Ni-based superalloys for gas turbine blade due to their high melting point and excellent oxidation resistance, as well as mechanical properties including a higher service temperature than that of Ni-based superalloys. In previous research, most Mo-Si-B alloys have been fabricated by casting and mechanical alloying method, which have some problems concerning the presence of non-equilibrium phase, difficulty in controlling the microstructure, impurities during the process, and so on. In this work, mechano-chemical process to fabricate two phases intermetallic powders (Mo5SiB2 and Mo3Si) was carried out as an initial stage of research for controlling the microstructure of Mo-Si-B alloys. This method uses starting powders of MoO3, Si3N4 and BN and includes the stages of ball-milling for mechanical mixing and refinement and chemical reactions during reduction and continuative heat treatment under hydrogen atmosphere.