The distribution of Y₂O₃ during selective laser melting of IN625/Y₂O₃ core-shell powders

Selective laser melting (SLM) of metal-oxide hybrid powder is currently a cost-effective approach for fabricating oxide-dispersion-strengthened alloys. The distribution behavior of oxide during the SLM process has significant effects on the performance of the final components. In this work, Y₂O₃ strengthened IN625 superalloys were fabricated by selective laser melting using IN625 powder coated by 1 wt% and 3 wt% Y₂O₃. The hybrid powder prepared by the resonant mixing method present the good flowability. Due to the high melting point of Y₂O₃ powder and its harmful effect on the wettability between the melt track and the formed surface, the required laser energy density for successful SLM-fabrication of the hybrid powder should be high. The distribution characteristics of Y₂O₃ during the SLM process and the corresponding evolution mechanism were analyzed. It was found that severe loss of Y₂O₃ occurred during SLM process, resulting from Y₂O₃ slag on the top surface of the built specimen, Y₂O₃ adhered to spatter particles falling into the recycling powder, and Y₂O₃ plume blown into the machine filter by the gas flow. The more Y₂O₃ coated on the metal powder, the more Y₂O₃ lost during SLM. The molten pool with keyhole mode is favorable to reduce Y₂O₃ loss compared to the conduction mode.