Effects of isothermal heating procedure and strontium addition on semisolid forming of AZ91 magnesium alloy

A two step isothermal heating process was developed to prepare a semisolid slurry of AZ91 alloy. In the process the alloy was heated isothermally at its liquidus temperature, cooled to a semisolid temperature, and then heated isothermally at the temperature before it was deformed. This relatively simple method was found to be a highly efficient way to generate a non-dendritic microstructure. The influence of strontium addition on the soundness of semisolid formed parts was also studied. AZ91 alloy is prone to shrinkage porosity because the freezing range of the alloy is wide. Porosity formation during the process was observed to be suppressed by the microaddition of strontium.