球磨时间对机械合金化制备NbMoTaW高熵合金粉末的影响

Effect of Milling Time on Preparation of NbMoTaW High Entropy Alloy Powder by Mechanical Alloying

采用机械合金化技术制备了NbMoTaW高熵合金粉末,研究了球磨时间对粉末相结构、微观形貌、杂质含量、颗粒粒径的影响。利用X射线衍射仪、扫描电镜和透射电镜对高熵合金粉末进行了物相和形貌分析,利用能谱仪定量分析粉末中元素分布和杂质含量,利用激光粒度仪测试了粉末颗粒尺寸分布。结果表明:随球磨时间增加,混合粉末经历了扁平化、冷焊断裂、球形化3个阶段,球磨45h后,形成了具有单一bcc结构的高熵合金粉末。粉末形貌从初始的不规则状转变成片状,而后转变成椭球状,且球形度不断优化。杂质主要来源于球磨罐和磨球,不同球磨时间段,杂质含量增速不同。颗粒粒径随球磨时间变化,呈现出先增大后减小的趋势,且颗粒粒径分布更为均匀。

NbMoTaW high entropy alloy powders were prepared by mechanical alloying. The effects of milling time on the powder phase structure, microstructure, impurity content and particle size were studied. The phase and morphology of the high-entropy alloy powder were analyzed by X-ray diffraction, scanning electron microscopy(SEM) and transmission electron microscopy(TEM). The element distribution and impurity content in the powder were quantitatively analyzed by the energy spectrum analyzer. The particle size distribution of the powder was measured by the laser particle size distribution tester. The results show that the mixed powder undergoes three stages with milling time increasing: flattening, cold welding breakage, and sphericity. After 45 h ball milling, the powder forms a single bcc solid solution. The powder morphology changes from an initial irregular shape to a sheet shape, and then it changes into an ellipsoidal shape. Meanwhile, the sphericity is gradually optimized. The impurities mainly originate from the agate jar and the grinding ball. The powders after different ball milling time show different impurity content growth rates. The particle size changes with milling time, showing a trend of increasing first and then decreasing, and the particle size distribution is more uniform.