The behavior of thermal diffusivity change according to the heat treatment in Al-Si binary system

Thermal diffusivity was measured by laser flash analysis (LFA) to evaluate the effect of silicon in an aluminum-silicon binary alloy. Thermal diffusivity is related to thermal conductivity, and these parameters are strongly interdependent in alloy composition. Aluminum alloys with silicon contents of 1 wt% and 9 wt% Si were produced by gravity casting. The alloys were solution-treated at 530 °C to modify the eutectic silicon and produce a solid solution. In this process, the eutectic silicon changed from the needle to the spherical phase in the Al-9.5 wt% Si alloy. The casted specimens were annealed at 345 °C to remove dissolved silicon and generated a stable microstructure. The heat-treated specimens were analyzed by laser flash analysis in dynamic mode. The thermal diffusivity increased as decreased the dissolved silicon atoms in aluminum matrix. The thermal diffusivity also increased when isothermal method test at 530 °C due to silicon separation in Al-9.5 wt% alloy.