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

• A core-shell intermetallic powder consisting of Mo particles surrounding the intermetallic compound (Mo5SiB2 and Mo3Si) particles was prepared by a mechano-chemical process and a CVT process.
• A Mo-Si-B alloy that has uniformly distributed intermetallic compound phases (Mo5SiB2 and Mo3Si) in the matrix phase of α-Mo was fabricated successfully.

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 α-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 α-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 α-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 α-Mo phase uniformly embedded by intermetallic compound phases, was fabricated by the pressureless sintering of the core–shell intermetallic powder.

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