Developing light-weight high-strength Al matrix composites with voids via the interface and heterostructure design

In this study, 10 vol.% hollow glass microspheres (HGMs) reinforced Al-Mg-Si-Cu matrix composite were fabricated via powder metallurgy. Through deliberate interface design, in-situ high-strength spherical shells and near-coherent interfaces were achieved. A heterostructure (HS) formed between the shell and matrix regions, where thermal mismatch activated hetero-deformation-induced (HDI) strengthening, promoting abundant intragranular dislocation cell formation near interfaces and enhancing strength. Remarkably, the foam-structured composite achieved a yield strength of 330 MPa—an alloy-grade level—while reducing density by 0.178 g/cm3 at no additional cost. This work demonstrates a simple yet effective paradigm for lightweight aluminum structural materials.