Dynamic response and fracture of B₄C/6061 Al composites: experiments and simulations

In this study, B₄C/6061 Al metal/ceramic composites (MCCs) with a ceramic content of 75 vol% are fabricated using the vacuum gas pressure infiltration method. The compressive and tensile behaviors under quasi-static and dynamic loading are investigated through compression tests and Brazilian disc tests, respectively. The composites demonstrated significant strain rate sensitivity, with compressive strength rising from 866 MPa (0.001 s⁻¹) to 1093 MPa (600 s⁻¹) and tensile strength from 151 MPa to 206 MPa (900 s⁻¹). The JH-2 constitutive model effectively simulates the compressive/tensile responses of 75 vol% B₄C/6061 Al MCCs, with numerical results demonstrating excellent agreement with experimental data. The significant differences in compressive/tensile strengths under varying strain rates lead to distinct macroscopic fracture modes in the composites. Furthermore, the study reveals that under dynamic compression, the composite transitions from 60° shear failure at low strain rates to biconical structural fragmentation at high strain rates. Fracture morphology analysis reveals the primary microscopic failure mechanisms, including transgranular fracture of B₄C particles, particle pull-out, dimple fracture of the Al matrix, crack deflection, and crack bridging. These microstructural characteristics, such as interfacial debonding and crack bridging via the Al phase, collectively delay material fracture and enhance energy dissipation capacity.