Fabrication of diamond/AlSi10Mg composite using SLM: Effects of processing parameters and pre−/post-treatments

Abstract

Diamond reinforced aluminum is a promising thermal management material for electronics applications because of an excellent combination of high thermal conductivity and low density. Since diamond reinforced aluminum is difficult to machine due to high hardness, it is attractive to manufacture diamond/aluminum composite parts with complex structures using additive manufacturing (AM) technology. However, the effect of the AM process on the thermal properties of diamond reinforced aluminum is unclear so far. In this study, selective laser melting (SLM) was used to prepare a diamond/AlSi10Mg composite with different diamond contents. The effects of pre-treatments of the diamond particles and post heat treatments of the SLMed samples were also investigated. It was found that the SLMed diamond/AlSi10Mg indeed possessed an enhanced thermal conductance than the pure AlSi10Mg. However, there were aspects that differentiated the SLMed diamond/AlSi10Mg from that fabricated by conventional processes. Increasing the diamond content from 15 wt% to 30 wt% did not further increase the thermal conductivity as it resulted in higher porosity of the SLMed samples. A pre-treatment of Ti coating on the diamond particles, a commonly used technique for conventional diamond/aluminum composite processing, was found to be unhelpful for the thermal property, as the diffusion of Ti into the aluminum matrix during SLM reduced the matrix thermal conductivity. On the other hand, the post heat treatments significantly increased the thermal conductivity of the SLMed samples by reducing the solute concentration.