Thermal Properties of Selectively Laser-Melted AlSi10Mg Products with Different Densities

The thermal diffusivity and thermal conductivity of selectively laser-melted AlSi10Mg samples with different target relative densities, 99 and 99.5%, have been studied in the temperature range from 25 to 400 °C. The properties were measured in the build direction and orthogonal to the build direction, for the samples in the as-built and heat-treated conditions. The 99.5% dense samples are characterized by a noticeably higher thermal diffusivity and higher thermal conductivity than the 99% dense samples. For each sample, it is found that the applied heat treatment improves the thermal diffusivity and thermal conductivity of the as-built material, but also results in pronounced anisotropy, with greater thermal diffusivity and conductivity in the build direction, especially for the 99.5% dense sample. The anisotropy is attributed to the presence of Si particles along the grain boundaries of columnar grains. Since the columnar grains are elongated along the build direction, a smaller spacing between particle-decorated boundaries in the plane perpendicular to the build direction presents a higher resistance to the heat conduction.