Effects of heat treatment on the thermal properties of AZ91D magnesium alloys in different casting processes

The thermal diffusivity and specific heat capacity of semi-continuous casting (SC) and high-pressure die-casting (HPDC) magnesium alloys before and after T4 and T6 heat treatments were measured at room temperature, and their thermal conductivity was calculated. The effects of heat treatments on the thermal properties of AZ91D alloys in different casting processes were investigated, and the mechanism of the effects was also discussed. Before heat treatment, the HPDC alloys had higher thermal conductivity than that of the SC alloys. Moreover, heat treatment after forming had a remarkable influence on the thermal properties of the SC and HPDC alloys. T4 treatment had negative effects on the thermal conductivity of the SC and HPDC AZ91D alloys, and the T6 heat-treatment SC and HPDC alloys had higher thermal conductivity than that of the T4 treatment alloys.