Hierarchical reinforcement strategy enables aluminum matrix composites with uncompromised high-temperature mechanical...

An aluminum matrix composite with enhanced high-temperature strength and modulus is developed in this study using powder metallurgy, incorporating high-energy ball milling-controlled in-situ reactions between the Ti₂AlC (MAX phase) precursor and aluminum (Al) matrix. High-energy ball milling induces a dual-pathway elemental diffusion architecture in Ti₂AlC, enabling the internal decomposition mechanism in Ti₂AlC and producing a hierarchical microstructure. This structure contains (1) 0.42 μm and 38.6 vol.% Al₃Ti particles uniformly dispersed in the Al matrix (0.32 μm), and (2) intraparticle carbon-contained clusters and rod-like phases (2-100 nm), enhancing Al₃Ti strength. This multi-level architecture achieves high strength and stiffness at elevated temperatures, with ultimate tensile strength values of 632 MPa (room temperature) and 246 MPa (350 °C) and corresponding Young's modulus values of 124 GPa and 106 GPa, respectively. At 350 °C, the specific modulus of the composite surpasses that of Ti (TC4), Cu (QZr0.2), steel (45 steel), and Ni (GH93) by 88%, 190%, 55%, and 42%, respectively, which positions it as a competitive candidate for lightweight structural materials in high-temperature applications.