Mechanical behaviors and deformation mechanisms of quasicrystal-reinforced 7075 aluminum alloy composites

Al₆₃Cu₂₅Fe₁₂ quasicrystal (QC) particle-reinforced 7075 Aluminum composites were fabricated via an advanced rapid hot-press sintering technology. The influences of QC content and strain rate on the yielding and plastic flow behaviors of the materials were systematically examined over a wide loading-rate range. The composites exhibit pronounced QC-content sensitivity and strain rate effect in both yield stress and flow stress, with the overall strength increasing as QC content and strain rate increase. Beyond the elastic limit, no distinct yield plateau is observed; instead, a gradual yielding behavior shows up. Detailed analyses show that the flow response is dictated by the dynamic competition among different mechanisms such as matrix strain hardening, load transfer between matrix and particles, and thermally induced softening, leading to QC-content-dependent flow characteristics. Finally, a rate-dependent yield-strengthening model is proposed based on the strain-rate sensitivity of the yield stress, enabling accurate prediction on the yield stress of composites with different QC contents, and providing quantitative support for the design and engineering application of QC-reinforced 7075 aluminum composites.