Microstructure and mechanical property of bimodal-size metallic glass particle-reinforced Al alloy matrix composites

A bimodal size metallic glassy particles reinforced 7075 aluminum composite was fabricated by powder metallurgy via ball milling and hot extrusion. The results show that metallic glassy reinforcements help to improve the densification due to the liquid-like behavior in the supercooled liquid region. The metallic glassy reinforcements were found to have a bimodal size distribution at nanoscale and microscale, and were uniformly distributed in the matrix. An interphase layer with a thickness of 60–80 nm was observed between the reinforcement/matrix resulted from elemental diffusion and chemical reaction. The introduction of bimodal size metallic glassy particles have significantly improved the mechanical properties, where the yield strength and fracture strength increase from 442 and 648 MPa for Al7075 to 869 and 962 MPa for composite with 17 vol% reinforcement, respectively. The strengthening mechanisms of the composites were revealed.