Additive manufacturing of an equimolar CoCrNi medium entropy alloy (MEA) by selective laser melting (SLM) was investigated, emphasizing its microstructure, properties, and metallurgical defects. It was found that SLM sample density exhibited a non-monotonic relation with their volume energy density (VED); the density first increased but then decreased while the input VED was gradually increasing. A maximal relative density of 98.9 pct was accessible at a VED of 83.3 J/mm³. X-ray diffraction indicated that the printed CoCrNi MEA exhibited an FCC single-crystal structure where the lattice constant decreased with the increasing VED owing to the evaporation of the Cr element in the SLM process. The average grain size gradually increased with increasing VED, irrespective of whether viewed from the top or the side of the printed part. Similarly, the residual stress increased with increasing VED, which produced more microcracks and deteriorated the tensile preformation of the printed samples, although the yield strength (630 MPa) showed no apparent difference at different VEDs. Owing to the ultrafine cell structure, the mechanical property of the SLM printed sample was twice that of cast or wrought CoCrNi MEA.

研究了通过选择性激光熔化（SLM）进行等摩尔CoCrNi中等熵合金（MEA）的增材制造，强调了其微观结构，性能和冶金缺陷。发现SLM样品密度与其体积能量密度（VED）呈非单调关系。当输入VED逐渐增加时，密度先增加，然后减少。VED为83.3 J / mm ^3时，最大相对密度为98.9 pct。X射线衍射表明，印刷的CoCrNi MEA表现出FCC单晶结构，其中由于SLM工艺中Cr元素的蒸发，晶格常数随VED的增加而降低。无论从印刷部件的顶部还是侧面看，平均晶粒度都随着VED的增加而逐渐增加。同样，残余应力会随着VED的增加而增加，这会产生更多的微裂纹，并使印刷样品的拉伸成形性能下降，尽管屈服强度（630 MPa）在不同的VED下没有明显的差异。由于具有超细孔结构，SLM印刷样品的机械性能是铸造或锻造的CoCrNi MEA的两倍。