La基非晶合金的固液自由能差估计

Estimation of Gibbs free energy difference for La-based amorphous alloys

根据热力学理论推导出了可以用于估计La基(如La55Cu15Ni5Al25,La55Cu10Ni5Al25Co5,La55Al25Ni20 and La55Cu10Ni10Al25)非晶合金固液自由能差的表达式。当La55Cu15Ni5Al25、La55Cu10Ni5Al25Co5、La55Al25Ni20和La55Cu10Ni10Al25的α值分别为0．52、0．3、0．2和0．15时,这个表达式给出的理论结果在很大的过冷区间几乎与实验测定结果重合,远远优于其它表达式给出的结果,并且其重合的最低温度可以分别达到350K(La55Al25Ni20)、450K(La55Cu10Ni5Al25Co5)、370K (La55Cu10Ni10Al25)和200K(La55Cu15Ni5Al25);另一方面,提出了用于估计非晶合金的库兹曼温度TA的表达式,即TA=Tmexp(α-1),发现此表达示估计的TA与通过实验数据计算出的吻合得很好。

We proposed an expression for the calculation of Gibbs free energy difference △G between the liquid and the crystal of multi-component bulk metallic alloys, such as La55Cu15Ni5Al25, La55Cu10Ni5Al25Co5, La55Al25Ni20 and La55Cu10Ni10Al25. In addition, it gives better results nearly overlapped with the experimental values over entire under-cooling range down to 350K for La55Al25Ni20, 450K for La55Cu10Ni5Al25Co5, 370K for La55Cu10Ni10Al25 and 200K for La55Cu15Ni5Al25 respectively when the a values are 0.52 for La55Cu15Ni5Al25, 0.3 for La55Cu10Ni5Al25Co5, 0.2 for La55Al25Ni20 and 0.15 for La55Cu10Ni10Al25 respectively. In addition, two Kauzmann temperature Tk s calculated by Eq.（3） and Eq.（12） respectively accord with each other, indicating that the Eq,（12） can be used for estimation of Kauzmann temperature Tk by the theoretical △G expression of metallic glasses, Moreover, the Kauzmann temperature Tk, fusion temperature Tm and isenthalpic temperature Tk are related by the expression Tk = Tm exp（a-1）.