Mg3Sb2金属间化合物的机械化学合成工艺

Mechanical and chemical synthesis process of Mg_3Sb_2 intermetallic compound

采用机械合金化方法制备Mg_3Sb_2金属间化合物,研究了摩尔比为3:2的Mg、Sb混合粉末的机械合金化过程,通过改变球磨转速和球料比找到制备Mg_3Sb_2的最佳工艺参数,对球磨后的粉末进行了X射线衍射(XRD)、差示扫描量热法(DSC)、扫描电镜(SEM)测试分析。结果表明,机械合金化方法可制备出细小的Mg_3Sb_2粉末,最佳球磨工艺参数是500 r/min的球磨转速、15:1的球料比。由热力学计算可知,Mg-Sb二元合成反应的绝热温度Tad=2149.5 K。DSC分析知,随球磨时间的延长,燃烧反应的临界温度会下降。经Kissinger公式计算原始混合粉末的激活能为94.45 k J/mol,球磨2 h之后的激活能为82.23 k J/mol,说明球磨使粉末内部产生大量晶体缺陷和位错等,体系能量增加,反应激活能降低,从而促进合金化的进程。

Mg3Sb2intermetallic compound was prepared by mechanical alloying and the alloying process of Mg and Sb mixed powders with a molar ratio of 3： 2 was studied. By changing the milling speed and ball-powder ratio,the optimal process parameters for preparing Mg3Sb2 were determined. The milled powders were analyzed by XRD,DSC and SEM. The results show that the fine Mg3Sb2 powders are prepared by mechanical alloying,and the optimal process parameters are ball milling speed of 500 r/min and ball-powder ratio of 15： 1.By thermodynamic calculation,the synthesis reactions adiabatic temperature of the Mg-Sb binary alloy is 2149. 5 K. DSC analysis shows that the critical temperature of the combustion reaction decreases with the increasing of the milling time. The initial mixed powders＇ activation energy is 94. 45 k J/mol,and after milling for 2 h,the activation energy is 82. 23 k J/mol through the calculation by the Kissinger formula,which shows that the energy of the system increases and the reaction activation energy reduces,and the alloying process can be promoted by the ball milling as a result of a large number of crystal defects and dislocations.