Addressing strength-ductility trade-off in heterogeneous B ₄ C/7075Al composites via powder size grading combining pressure infiltration

The strength-ductility trade-off is a persistent dilemma for Al matrix composites, limiting their practical applications. In this work, we present a novel strategy combining powder size grading with pressure infiltration to create heterostructures in B4C/7075Al composites, resulting in uneven distributions of B4C and a mix of fine and coarse grain regions. The heterogeneous B4C/7075Al composites exhibit a fracture elongation of 9.6%, comparable to that of 7075Al, while retaining an ultimate tensile strength close to their traditional homogeneous counterparts. The significant hetero-deformation induced stress, sufficient dislocation accumulation and effectively suppressed crack propagation are responsible for the balance between strength and ductility.