不同粒径粉末搭配对激光选区熔化成形件的质量起着至关重要的作用。为此,系统研究了IN738合金不同粒径粉末搭配对粉末特性和成形件质量的影响,结果表明,成形粉末流动性随着粗粒径粉末体积分数的增加而增加,当粗细粉末（50%粒径为31~53 μm的粗粉和50%粒径为15~30 μm的细粉）相互搭配时,其粒径分布为D10为15.1 μm、D50为27.9 μm、D90为52.9 μm,成形粉末具有较高的松装密度和振实密度,成形件具有较好的表面粗糙度及较低的孔隙率和裂纹密度,致密度达到99.3%。研究发现,不同粒径粉末搭配制备的打印件裂纹为凝固裂纹,裂纹主要沿着外延生长的〈001〉取向柱状晶晶界分布并扩展。

The combination of powders with different particle sizes plays a vital role in the quality of samples formed by selective laser melting. In this paper, the effect of IN738 alloy with different particle size powders on the powder characteristics and the quality of the shaped parts have been systematically studied. The results show that the powder fluidity increases with the increase of the volume fraction of the large particle size powder. When powders with large and small particle sizes （50% particle size of 31 μm to 53 μm and 50% particle size of 15 μm to 30 μm） are matched with each other, the particle size distribution shows that D10 is 15.1 μm, D50 is 27.9 μm, and D90 is 52.9 μm, the apparent density and tap density of the powder are higher. And the density of shaped part reaches 99.3%, with the better surface roughness and the lower porosity and crack density. The study exhibits that the cracks of the printed parts are solidification cracks, and the cracks are mainly distributed and propagated along the epitaxially grown 〈001〉 oriented columnar grain boundaries.