A forced convection stirring process for Rheo-HPDC aluminum and magnesium alloys

A simplified process, namely forced convection stirring (FCS), was proposed to prepare four different semisolid slurries of Al and Mg alloys. A simple rheological high pressure die-casting (Rheo-HPDC) process was developed by combining the FCS device with a HPDC machine. The temperature and composition fields of the melt in the FCS process were simulated. The microstructures and mechanical properties of the alloys formed by the FCS Rheo-HPDC were studied and compared with those formed by HPDC and other Rheo-HPDC processes. The results showed that the FCS process can prepare slurries in which the primary particles are fine, spherical and uniformly distributed in the matrix and the process can effectively suppress macrosegregation. The strong convection rapidly promotes the uniformity of the temperature and composition of the melt. Compared to HPDC and other Rheo-HPDC alloys, the alloys formed by FCS Rheo-HPDC have an improved ultimate tensile strength, yield strength, elongation and hardness, due to the refinement of microstructure and the decrease of porosity. Heat treatments can be utilized to further enhance the mechanical properties of FCS Rheo-HPDC alloys.