机械合金化+热压制备Laves相TaCr_2合金的物相演变及热力学分析

Phase Evolution and Thermodynamic Analysis of Laves Phase TaCr_2 Alloy Prepared by Mechanical Alloying Followed by Hot Pressing

采用Miedema模型研究了机械合金化(MA)+热压(HP)过程中Cr-33.3%Ta元素粉无序化、非晶化和有序化过程,结果表明,Cr-33.3%Ta物相演变过程中形成Laves相Ta Cr_2最稳定,其次是Ta(Cr)和Cr(Ta)固溶体,非晶态不稳定,形成过程伴随吸热。借助X射线衍射分析了MA和HP过程中Cr-33.3%Ta元素粉的物相演变,结果表明,MA+HP制备Laves相Ta Cr_2合金的过程中,Cr-33.3%Ta元素粉的物相演变为:Ta+Cr元素粉→无序Ta(Cr)和Cr(Ta)固溶体→非晶态→有序金属间化合物Laves相Ta Cr_2。Miedema模型计算结果与试验结果相符。

The process of disordering,non-crystallizing and ordering of Cr-33.3%Ta elemental powder in the course of mechanically alloying（MA）and hot pressing（HP）was investigated by using Miedema model.Results showed that Laves-phase TaCr2formed during the phase evolution of Cr-33.3%Ta was more thermodynamically stable than Ta（Cr）and Cr（Ta）solid solution,which were instable in amorphous state,with heat adsorption during the formation.The phase evolution of the Cr-33.3%Ta elemental powder during MA and HP was analyzed by X-ray diffraction.Results indicated that the process of the phase evolution was as follows：Ta＋Cr elemental powder→disordered Ta（Cr）and Cr（Ta）solid solution→amorphous state→ordered intermetallic compound Laves-phase TaCr2.The calculation result of Miedema model is consistent with the test result.