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

Abstract

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.