Al2O3 loss prediction model of selective laser melting Al2O3–Al composite

Abstract The element/phase loss is undesirable but existing during selective laser melting (SLM) of materials with volatile element/phase, which not only changes the material composition but also affects the molten pool flow. In the previous researches, the effect of remelting on the element/phase loss was neglected during the SLM process, instead, laser energy density was thought to be uppermost. In fact, the SLM process fabricates the parts in a manner of line by line and layer by layer, i.e., additive character, and the remelting in the overlap zone occurs during the SLM process. In this paper, three different Al2O3 loss prediction models of SLM Al2O3–Al composite by considering the additive character of SLM and the distribution of the Al2O3 associated with the different molten pool driving forces were developed. By comparing with the experimental results and predicted results, it is found that the Al2O3 is distributed on both sides of the molten pool under the combined action of the Marangoni flow and the evaporation recoil pressure. This kind of Al2O3 distribution enhances the effect of the remelting on the Al2O3 loss, i.e., the remelting brings a logarithmic increase in the Al2O3 loss rate. This determines the final Al2O3 loss rate of the SLMed 3D samples. During this study, although the Al2O3 loss rate of the single-track is only 33%, the loss rate of SLMed 3D samples increases significantly to 97% when the hatching space of 60 μm and scanning speed of 200 mm/s are utilized, i.e., almost no Al2O3 in the 3D sample. Thus, it is more important to reduce the remelting, i.e., overlap rate for reducing the element/phase loss. This study is a benefit for understanding and reducing the element/phase loss in SLM.