Cu-Zn 合金马氏体相变热力学

THERMODYNAMICS OF THE MARTENSITIC TRANSFORMATION IN Cu-Zn ALLOYS

假定 Cu-Zn 合金马氏体相变中新、旧原子存在 Bain 机制所示的对应关系,则沿用已知的热力学数据,以 BWG 模型处理 Cu-Zn 合金的有序问题,推导出相变驱动力ΔG^(β′→α′)的普遍表达式。以该式计算了Cu-Zn 合金马氏体相变的平衡温度 T(?)及马氏体相变点 M_s,其中 M_s 与实验结果很好吻合。计算证明,母相有序化是 Cu-Zn 合金发生热弹性马氏体相变的必要条件,有序度对 M_s 有显著的影响。

It is supposed that the correspondent relationship between atomsof the new and parent phases as shown in Bain mechanism exists in themartensitic transformation of Cu-Zn alloys.Applying the known values ofthermodynamic properties and treating the ordering problem of Cu-Zn alloys byBWG model,a general formula for driving △G^(?) of phase tansformation isderived.This formula is used to calculate the equilibrium temperature T_0 andthe starting temperature M_(?) of the martensitic transformation of Cu-Zn alloys,and the calculated M_(?) are in very good agreement with the experimental results.Calculations also indicate that the ordering of the parent phase is necessary forthe thermoelastic martensitic transformation in Cu-Zn alloys,and ordering degreehas tremendous influence on the values of M,.