二元不互溶Cr-Mo系高能球磨固溶研究

Research on Solid Solution of Cr-Mo Immiscible Binary System by High-Energy Ball Milling

摘要: 对Cr-62at.%Mo, Cr-35at.%Mo 和 Cr-15at.%Mo三种粉末进行机械合金化，探究粉末合金化过程中的形貌及物相变化。通过对粉末进行扫描电镜和X射线衍射分析发现，三种成份的混合粉末在高能球磨18 h后都实现了Cr、Mo的完全互固溶，形成具有不同固溶度的Cr(Mo)固溶体。根据Miedema模型，热力学计算结果表明：Cr-Mo二元系在平衡状态下不具备形成Cr(Mo)固溶体的热力学驱动力。而球磨过程中储存较多的能量有利于组元越过能垒形成Cr(Mo)固溶体。X射线衍射分析发现，形成的固溶体是置换固溶体。

Abstract: Morphologies and phase transition of three kinds of powders Cr-62at.%Mo, Cr-35at.%Mo and Cr-15at.%Mo synthesized by mechanical alloying at low-temperature were investigated. The milled powders were examined by scanning electron microscope (SEM) analysis and X-ray diffraction (XRD) phase analysis, respectively. The results showed that three kinds of powders milled for 18 h were composed of the Cr(Mo) solid solution with different solid solubility. Based on the Miedema’s model, the thermodynamic calculation indicated that under the equilibrium-state, Cr-Mo binary system has no thermodynamic driving force for forming Cr(Mo) solid solution. So, the energy barrier for forming Cr(Mo) solid solution could be overcome during mechanical alloying. XRD analyses showed Cr(Mo) solid solution synthesized by high-energy ball milling was sub-stitu- tional solid solution.