The effect of varying amounts of CoAl₂O₄ inoculant ranging from 0 to 2 wt pct on the microstructure evolution of Inconel 718(IN718) fabricated by selective laser melting (SLM) was evaluated. Characterization of the as-built microstructure revealed that addition of CoAl₂O₄ resulted in a modest degree of grain refinement with a slight increase in microstructural anisotropy. Increasing the total CoAl₂O₄ content beyond 0.2 wt pct resulted in severe agglomeration of the non-metallic particles and the formation of slag inclusions measuring up to 100 μm in size present in the as-built microstructure. In addition to large agglomerates, the inoculant was chemically reduced to form a fine dispersion of submicron-sized Al₂O₃ particles throughout the IN718 matrix. The fine dispersion of oxides significantly hindered grain recrystallization during the post-fabrication heat treatment due to a Zener pinning effect. The findings from this study indicate in order to effectively utilize CoAl₂O₄ as a grain refining inoculant for additive manufacturing, the process parameters need to be optimized to avoid agglomeration of the non-metallic particles and other process-related defects.

评估了0至2 wt pct范围内变化的CoAl ₂ O ₄孕育剂对通过选择性激光熔化（SLM）制造的Inconel 718（IN718）微观组织演变的影响。初生微观结构的表征表明，添加CoAl ₂ O _4会导致晶粒细化程度适中，而微观结构各向异性会略有增加。增加煤的总₂ ö ₄含量超过0.2重％导致非金属颗粒的严重附聚和夹渣的测量高达100的形成μ在建成的微结构中存在的尺寸为m。除大型团聚体外，还对孕育剂进行了化学还原，以使其在整个IN718基体中形成亚微米尺寸的Al ₂ O ₃微粒的精细分散体。由于齐纳钉扎效应，氧化物的精细分散显着阻碍了后加工热处理过程中的晶粒再结晶。这项研究的结果表明，为了有效地利用CoAl ₂ O ₄作为增材制造的晶粒细化孕育剂，需要优化工艺参数，以避免非金属颗粒的团聚和其他与工艺相关的缺陷。