(中南大学 材料科学与工程学院,长沙 410083)
摘 要: 以Miedema混合焓模型为基础,计算Al-Er和Si-Er二元合金的部分热力学函数,如混合焓∆H,过剩熵SE以及过剩吉布斯自由能GE以及各组元的活度。结合Al-Er和Si-Er二元相图计算了Al3Er和Er5Si3相析出反应的吉布斯自由能。结果表明:Al-Er和Si-Er二元合金的混合焓、过剩自由能与过剩熵在整个浓度范围内均为负值,各组元活度计算结果相对于理想熔体有较大的负偏差,说明Er原子与Al原子和Si原子都有很强的相互作用; Al3Er和Er5Si3相反应的吉布斯自由能均为负值,且Er5Si3相的反应吉布斯自由能比Al3Er相的小,因此Er加入到Al-Si合金中会优先与Si生成Er5Si3相,过剩的Er才与Al生成Al3Er相。
关键字: Al-Er;Si-Er;Miedema混合焓模型;活度
(School of Materials Science and Engineering, Central South University, Changsha 410083, China)
Abstract:Based on the Miedema formation enthalpy model, the enthalpies of formation, excess entropies, excess free-energy and the activity among all components of Al-Er and Si-Er binary alloy were calculated. The results show that their values are all negative. Compared to an ideal solution, the activity has a larger negative bias, which indicates that Er has stronger interaction with Al and Si. According to the binary phase diagram of Al-Er and Si-Er, the Gibbs free-energy of the precipitation of Al3Er and Er5Si3 are deduced. The Gibbs free-energy of reaction of Al3Er is lower than that of Er5Si3, so Er5Si3 forms priority to Al3Er, and then the excess Er reacts with Al and form Al3Er.
Key words: Al-Er; Si-Er; Miedema formation enthalpy model; activity