Breaking the strength-ductility trade-off in aluminum matrix composite through "dual-metal" heterogeneous structure and interface control

Abstract

Heterogeneous microstructure design has been a prevalent strategy for breaking the strength-ductility dilemma in structural materials. However, it is still difficult to achieve customizable heterogeneous microstructures. Here, we employ a simple powder metallurgy method to construct "dual-metal" heterogeneous structure in aluminum matrix composite (AMC) by introducing hard high-entropy alloy particles into the soft aluminum matrix. By using mutual diffusion and self-organization strategies, reinforcements with special core-shell structures were synthesized in situ, forming multi-level heterogeneous structures within the composites. The results show that the heterogeneity of the microstructure plays an effective role in regulating the strain gradient and maintaining significant strain hardening ability during plastic deformation. In addition, the nanograin layer of the core-shell reinforcement outer shell possesses good toughness and stress-bearing capacity, enabling it to accommodate deformation and inhibit crack propagation effectively. This study provides a feasible method for designing AMCs with heterogeneous structures and contributes a conceptual framework for designing strong and ductile metal matrix composites.