紧耦合真空气雾化制备Fe-Cr合金粉末的特性表征

采用紧耦合真空气雾化法制备Fe-Cr合金粉末,通过不同目数的筛网进行筛分,得到0~25 μm、25~53μm、53~105 μm、105~150 μm四个粒度段的粉末.使用氧氮分析仪、碳硫分析仪、电感耦合等离子体发射光谱仪分析雾化前后粉末化学成分,测定全粒度段及各粒度段的氧含量变化情况;采用扫描电镜、激光粒度仪等分析测试手段观察粉末表面形貌及表面微观组织并测定粉末粒径.结果表明:紧耦合真空气雾化制备Fe-Cr金属粉末化学成分可精确控制,全粒度段氧含量为0.024wt.%;冷却速度随粉末粒径的减小呈现指数级增长,随着粉末粒度段的增大,表面组织主要由胞状晶、柱状晶向树枝晶发展;各粒度段氧含量随粒径增大逐渐减小;空心粉的形成主要与袋式破碎机制和晶粒凝固收缩差有关.

Characterization of Fe-Cr alloy powder prepared by close-coupled vacuum induction melting gas atomization

Fe-Cr alloy powders were prepared by close-coupled vacuum induction melting gas atomization and shifted through different mesh sizes to obtain powders with four particle size segments of 0-25 μm、25-53 μm、53-105 μm and 105-150 μm. Oxygen and nitrogen analyzer, carbon and sulfur analyzer and inductively coupled plasma emission spectrometer were used to analyze the chemical composition of powder before and after atomization, and the change of oxygen content in all particle size segments and each particle size segment. SEM and laser particle size analyzer were used to observe the surface morphology and microstructure of powder and determine the particle size. The results showed that the chemical composition of Fe-Cr metal powder prepared by close-coupled vacuum induction melting gas atomization can be precisely controlled, and the oxygen content in full-size section was 0.024wt.%. The cooling rate increased exponentially with the decrease of powder particle size. With the increase of powder particle size segment, the surface structure mainly developed from cellular and columnar crystals to dendritic crystals. The oxygen content in each grain size segment decreased with the increase of grain size. The formation of hollow powder was mainly related to bag crushing mechanism and grain solidification shrinkage difference.