Solution treatment of core-shell structured particle reinforced A356 composite prepared by powder thixoforming: Effects of partial remelting temperature

In-situ core-shell structured particle Ti@(Al–Si–Ti)_p reinforced A356 Al alloy matrix composites were prepared by powder-thixoforming at different partial remelting temperatures, and then were solid solution treated at 545 °C for 1 h. The results indicate that the reaction between Ti cores and Al matrix operates to form nano τ₂ particles during solutionization, while the original (Al, Si)₃Ti phases transform into τ₂ phases, and simultaneously, the early-formed nano τ₂ particles grow into large-sized plates. These behaviors are enhanced with rising the remelting temperature. The content of eutectic Si and solubility of Si in α-Al phase in the solutionized composites further decrease with rising remelting temperature, due to the reaction and phase transformation, and de-dissolution of Si, respectively. The tensile properties of the solutionized composites first increase and then decrease as the temperature rises, and the composite thixoformed at 595 °C has the highest comprehensive mechanical properties, an ultimate tensile strength of 267.0 MPa, yield strength of 178.6 MPa and elongation of 21.0 %, increased by 3.1 %, 13.3 % and 15.4 % compared with those of the as-fabricated counterpart.