Achieving strength-ductility synergy in semi-solid squeeze cast 6TiB2/Al–17Si–4Cu composites by heat treatment

This study aims to achieve synergistic strength-ductility enhancement of semi-solid squeeze cast 6TiB 2 /Al–17Si–4Cu composites through in-situ particle strengthening and T6 heat treatment. The microstructure and mechanical properties of 6TiB 2 /Al–17Si–4Cu composites with different heat treatments were investigated. TiB 2 particles are semi-coherent with α-Al and primary Si, respectively. The nanoscale precipitate phases were determined by their crystal orientation relationships. The results showed that they are θ and θʹ phases. Meanwhile, the research results pertaining to the mechanical properties imply that the strength and ductility are enhanced by the TiB 2 particles and Al 2 Cu precipitates. The optimum heat treatment process (solution treatment for 9 h at 520 °C and aging for 8 h at 170 °C) of strengthened 6TiB 2 /Al–17Si–4Cu composites is revealed in this study, when the ultimate tensile strength and elongation of the composites are 263.3 MPa and 0.51%, respectively. The mechanisms governing the enhanced strength and ductility of 6TiB 2 /Al–17Si–4Cu composites were discussed.