Characterization and Analysis of the Thermal Conductivity of AlSi10Mg Fabricated by Laser Powder Bed Fusion

Laser-based powder bed fusion (L-PBF) of AlSi10Mg can be used to fabricate complex, light-weight structures with high thermal conductivity. Much effort has gone into investigating the mechanical behavior of L-PBF components; however, few studies investigated their thermal properties. This investigation characterizes the effect of process parameters on the relative density and thermal conductivity of L-PBF AlSi10Mg. Exposure time, laser power, pointwise distance, and build orientation were examined. Results show that changing these parameters can affect the thermal conductivity by up to 22%. For example, build orientation and pointwise distance influenced the thermal conductivity by 12.9% and 10%, respectively. As the pointwise distance increased, both the conductivity and the distance between the melt pool boundaries decreased, whereas the laser power had a negligible effect on both. The effect of exposure time was mainly dependent on the pointwise distance. It is shown that thermal conductivity is not only related to the relative density of the samples, but the number of the melt pool boundaries in the microstructure also plays a significant role in interrupting the heat flow. A new factor is introduced to account for the number of melt pool boundaries per unit length in the direction of heat flow, which helps to explain the variation in thermal conductivity for samples manufactured with high energy densities which had almost negligible difference in relative density.