超音速气雾化制备316L不锈钢粉末的表征

Characterization of 316 L stainless steel powders produced by supersonic gas atomization

利用自行研制的超音速雾化技术制备了316L不锈钢粉末,采用激光粒度仪、扫描电镜、金相显微镜和X射线衍射仪进行了表征.结果表明,316L不锈钢粉末的平均粒度约为24μm,粒度分布的几何标准偏差δ为1.75;粉末内部存在三种典型凝固组织,即具有发达二次枝晶的枝晶组织、胞晶组织以及枝状晶与胞状晶的混合组织;大粒径气雾化316L不锈钢粉末为单一的γ奥氏体相,小粒径粉末由γ奥氏体相+少量δ铁素体相共同组成;熔滴的冷速随着粒径的减小而提高,平均冷却速率为104～107K.s-1.

316 L stainless steel powders were prepared by supersonic gas atomization.The characteristic of the powder particles was investigated by means of laser particle size analyzer,scanning electron microscopy（SEM）,optical microscopy（OM）and X-ray diffraction（XRD）technique.The result indicates that the mass median particle diameter is about 24 μm and the geometric standard deviation δ is 1.75.Three main types of solidification microstructures were observed in the powders：well-developed dendrite,cellular and a mixture of dendrite and cellular.XRD measurements show that γ-austenite phase is found in the big particle while small particle is a composite consisting of δ-ferrite and γ-austenite phases.The cooling rate is inversely related to the particle size,i.e.,it increases with decreasing particle size.The mean cooling rates of melt droplets range from 104 to 10^7 K·s^-1.