Microstructure evolution of in situ Mg2Si/Al-Si-Cu composite in semisolid remelting processing

A semisolid of in situ Mg2Si/Al-Si-Cu composite is fabricated by strain-induced melt activated (SIMA) process, and the effects of isothermal holding time at the temperature of 580 °C and compression ratio on microstructure of the material are investigated. The result shows that the morphology of primary Mg2Si phase is identified as globular and/or elliptic with an average particle size of 25-30 μm. Furthermore, the morphology of α-Al grain from rosette type changes to globular and its size increases as the increasing of isothermal holding time. With the increasing of compression ratio, the morphology of α-Al grain becomes more globular and its size decreases.