Microstructure‐Controlled Crack Propagation and Fracture Resistance in MoSiBTiC Alloy Revealed by Multiscale Extended Finite Element Method Modeling

In view of the influence of microstructure on the fracture resistance of MoSiBTiC alloys, the extended finite element method (XFEM) was used to investigate the crack propagation behavior and local fracture response of the alloy, and subsequently to evaluate the effects of microstructural morphology on fracture resistance. A finite element analysis (FEA) model was employed to characterize the macroscopic fracture response of the homogenized alloy and to calibrate the effective fracture‐related parameters. In combination with nanoindentation and inverse analysis, the elastoplastic properties of the constituent phases were determined, and their averaged effective cohesive parameters were further calibrated using a simplified local fracture model. Furthermore, a multiscale FEA model was established based on the four‐point bending test, and the microcrack paths were compared with experimental results. It was found that the fracture process of the alloy involves the interaction of multiple mechanisms. In addition, the variation in fracture resistance cannot be explained solely by the volume fraction of the ductile phase, based on the local fracture simulations with ideally bonded interfaces. In contrast, particle arrangements promoting more symmetric stress distributions, more regular particles with higher circularity and lower aspect ratio, tend to be associated with higher fracture resistance of the alloy.