变价稀土元素对镁合金熔体中镁元素活度的影响

Effect of Changeable Valence Rare Earth Elements on Activity of Mg in Binary Alloy Melts

根据Miedema二元合金生成焓模型,结合相关热力学数据,对Mg-Eu,Mg-Yb的四个变价二元合金体系中镁元素的活度进行计算。结果表明,对这四个合金体系,低价稀土金属元素将使镁的活度变化曲线对理想溶液曲线产生正偏差,而低价稀土元素体系将出现负偏差。控制不同价态稀土元素的添加量将可在一定范围内控制合金熔体中镁的活度。

Based on Miedema for calculating the formation heat of binary alloy system, the activity of each and every binary system in the Mg - Eu alloy system and Mg - Yb alloy system were calculated combining with related thermodynamic data. The calculation results showed that, in the four binary systems, the lower- valence rare earth ele- ments will make the activities of Mg have positive deviations to the ideal curve, on the other hand, the higher- valence rare earth elements will make them negative deviations. Therefore , limiting the quantity of changeable valence rare earth elements that added will control the activity of Mg in every binary system in a certain range.