Insight to agglomeration and chemical reactions of CoAl2O4 inoculants in IN718 processed by selective laser melting

The investigation aims to clarify the influence of scan parameters on morphology and phase constitution CoAl2O4 inoculants in Inconel 718 (IN718) superalloy processed by selective laser melting (SLM). Gas atomized IN718 powder feedstock was uniformly blended with 0.2 wt% flakes a range understand effect inoculant additions microstructure. Similar reactions observed investment cast Ni-superalloys, particles were found chemically react elemental Al, Cr, Ti present melt pool become reduced into Al2O3, Cr2O3, TiO2 oxides after SLM process. Analyses single beads revealed existence Co-rich metallic distributed along surface oxides. However, since processing involves remelting previously deposited layers minimize occurrence porosity, this results dissolution that form when are pool. As such, ability Co contribute grain refinement becomes limited during processing. Furthermore, agglomerate direction. underlying mechanisms can be attributed Marangoni convection following moving center beam. It decreasing energy density increasing speed effectively reduce size number agglomerated oxide particles. Faster velocities lead convective flow within tendency for agglomeration. magnitude input time over which could This led formation lack fusion defects incomplete chemical reaction between effectiveness as-built microstructures is strongly dependent physics conditions.