Finite Element Analysis for the Effect of Microstructure Morphology on Microcracks and Deformability of MoSiBTiC Alloy at Room Temperature

The first−generation MoSiBTiC alloy, 65Mo-5Si-10B-10TiC (at%), consists of Mo solid solutions (Mo_ss), Mo₅SiB₂, TiC, and Mo₂C phases. The fracture toughness of this alloy has always been a concern that needs to be enhanced in this alloy to reduce the risk of brittle fracture failure. In the present study, the effect of constituent-phase morphology on the micro-crack initiation and propagation was investigated by finite element method (FEM). The FEM model was established based on the back-scattered electron image of the MoSiBTiC alloy. Continuum elements were used to model the constituent phases, while the cohesive elements were used to model debonding at the interfaces of the constituent phases, and the cleavage fracture within the brittle phases, Mo₅SiB₂, TiC, and Mo₂C. It was found that the brittle phase particles with higher roundness, lower aspect ratio, and smaller size contribute to a more uniform deformation of the microstructure under loading and maintaining the stability of the alloy. Additionally, the ductile Mo_ss phase isolating the brittle phases played a key role in improving the toughness of the alloy.