Micromechanics-based simulation of B₄C-TiB₂ composite fracture under tensile load

Micromechanics modeling was performed to study the effects of thermal residual stress, weak interphases, TiB₂ volume fraction and particle size on the mechanical responses and fracture behaviors of B₄C-TiB₂ composites. Experimentally observed fracture behaviors including micro-cracking and crack deflection were successfully captured. The weak interphases at B₄C-TiB₂ boundaries and the thermal residual stress induced during cooling by the large CTE mismatch between B₄C and TiB₂ were identified as two major factors to promote micro-cracking that caused the enhanced progressive failure behavior. Micro-cracking was enhanced with higher TiB₂ volume fraction due to higher fraction of weak interphase and material affected by thermal residual stress. Meanwhile, micro-cracking behaviors exhibited limited change with varying TiB₂ particle sizes. This modeling study successfully captured the main fracture behaviors and their trends by varying micro-structures of B₄C-TiB₂ composites and can potentially aid microstructure design of tougher B₄C-TiB₂ composites in the future.