Quantitative evaluation of microstructure in Mo-Si-B-TiC alloy produced by melting and tilt casting method

Abstract

Mo-Si-B-TiC alloys have been produced as candidates for a ultrahigh-temperature materials to replace Ni-base superalloys. We have quantitatively investigated the microstructure of a Mo-Si-B-TiC alloy composition. Mo-5Si-10B-10TiC (65Mo alloy) (at%) produced via arc-melting and tilt casting techniques. The starting material was composed of four constituent phases: Mo solid solution (Moss), Mo5SiB2, (Ti, Mo)Cx, (Mo, Ti)2C, and their eutectic (or peritecteutectic) phases. The compositions of these constituent phases were determined by EPMA. SEM-EBSD measurements revealed that T2 and (Ti, Mo)Cx phases have orientation relationships with Mo phase: {11-0}Mo//(001)T2, 〈111〉Mo//〈100〉T2 and {11-0}Mo//{11-1}(Ti, Mo)Cx, 〈111〉Mo//〈110〉 (Ti, Mo)Cx. Furthermore, 3-dimensional SEM examination combined with the FIB serial sectioning technique demonstrated that the T2 phase had a thin plate shape of orientation (001) for the plate surfaces and {100} for side ones.