Effect of the precipitation of secondary phases on the thermal diffusivity and thermal conductivity of Al-4.5Cu alloy

Abstract

The effect of the precipitation of secondary phases on the thermal properties of Al-4.5Cu alloy (in wt%) after various heat treatments was investigated using a laser flash apparatus (LFA). The alloy samples were solution treated at 535 °C for six hours followed by warm water quenching and then aged in air at 200 °C for different times. The results showed that the thermal diffusivity of the annealed sample increased relative to that of the as-cast sample in the temperature range from 20 to 260 °C. The thermal diffusivity improved as the solute concentration in the α-Al matrix rapidly decreased. The solution treated sample showed lower thermal diffusivity and conductivity than the artificially aged sample. The thermal conductivity of the solution treated sample was 148 W/m·K at 25 °C, but artificial aging treatment increased it to 166 W/m·K at the same temperature. The thermal diffusivity and thermal conductivity increased in the temperature range between 250 and 400 °C. This increase is due to the precipitation of secondary phases. Precipitation of secondary phases occurred as the temperature increased, which we confirmed via DSC analysis.