Experimental consideration on single phase regions at 1800 ?Cin Mo-rich portion of Mo-Si-B phase diagram

摘要

For the Mo-Si-B system, the phase diagrams published so far are only at 1600 ° C. Nowotny et al. first reported the phase diagram in 1957. Some replacements were performed by Perepezko and his coworkers in 1997 and 2006. However, there are some differences between them, especially near the region of Mo_5SiB_2, so-called T_2 phase. T_2 single phase region in the Perepezko's has a B-richer composition than that in the Nowotny's. However, there is a need for a new phase diagram at higher temperature with the requirement of phase stabilization above 1600 ° C for the turbine blade application of Mo-Si-B system. It was observed in our previous studies on the Mo-Si-B system that drastic microstmcture development occurred through heat treatment at 1800 °C for 24 h. Therefore, the purpose of this work is to experimentally investigate single phase regions at 1800 ° C in the Mo-rich portion of the Mo-Si-B phase diagram compared with the phase diagram at 1600 ° C.