Tailoring High-Entropy Oxides to Ameliorate Interfacial Mismatch of Aluminum-Matrix Composites Towards Superior Strength-Ductility Balance

The attainment of both strength and ductility is a vital requirement for most structural materials; unfortunately, these properties are generally mutually exclusive. Tailoring the interfacial relationship is often an effective method to address the "strength-ductility trade-off" phenomenon in metal-matrix composites. Herein, we proposed an optimization strategy to prepare aluminum-matrix composites reinforced with high entropy oxides (HEOs). Leveraging the compositional tunability of HEOs, their crystal structure and lattice parameters were customized to tailor the interfacial compatibility with aluminum matrices. High phase stability and significant lattice contraction over a broad range were achieved by doping with low valence state Li1+. The reduction in the theoretical lattice parameter mismatch from 4.3 % to 2.2 % ameliorated the experimental interfacial mismatch from 9.7 % to 4.3 %, thereby facilitating the transformation from semi-coherent to coherent interfaces. The mechanical properties exhibited an ultimate tensile strength of 348 +/- 7 MPa, coupled with an elongation of 27 +/- 1 %. The amelioration of the interfacial mismatch between reinforcements and matrices offers a novel design strategy for the preparation of aluminum-matrix composites towards synergistic high strength and ductility.