Microstructure control of Mo-Si-B alloy for formation of continuous alpha-Mo phase

Abstract

The Mo-Si-B alloy has been in the spotlight as a promising alternative to Ni-based superalloys due to its superior thermal resistance and mechanical properties. In particular, the mechanical properties of the Mo-Si-B alloy are sensitively influenced by the mutual distribution of the ductile alpha-Mo phase and brittle intermetallic compound phases such as Mo5SiB2 (T2) and Mo3Si (A15). For the Mo-Si-B alloy to possess an excellent fracture toughness, ductile alpha-Mo phase should form a continuous phase with the uniformly distributed intermetallic compound phases. In this study, a core-shell intermetallic powder composed of nano-sized alpha-Mo particles surrounding intermetallic compound particles was fabricated using Mo-Si-B intermetallic compound powders prepared through the mechano-chemical method and the chemical vapor transport (CVT) process of Mo oxide powder. Also, the Mo-Si-B alloy, which has a continuous alpha-Mo phase uniformly embedded by intermetallic compound phases, was fabricated by the pressureless sintering of the core-shell intermetallic powder.