基于液态合金短程序的混合构型熵新模型

A New Model for the Configurational Entropy of Mixing in Liquid Alloys Based on Short-Range Order

基于液态合金化学短程序与拓扑短程序发展了一个新的混合构型熵计算模型,从这个模型可以导出用来描述等原子直径随机混合物的理想混合熵.通过将该模型应用于一些理想的和真实的液态二元合金,可以看到化学短程序减小了混合构型熵,而原子尺寸差异的影响则较为复杂.当大原子进入小原子基体时,混合构型熵增大;而当小原子进入大原子基体时,混合构型熵减小.在这些合金中,共晶成分处并没有出现混合构型熵极大值.

A new model has been developed to calculate the configurational entropy of mixing in liquid alloys involving consideration of chemical and topological short-range order. The entropy of mixing for an equiatomic random mixture was naturally reached by this model. The application of this model to both hypothetic and real binary liquid alloys demonstrated that the chemical short-range order always decreased the configurational entropy of mixing, whereas complicated behavior was found with the atomic size effect. The configurational entropy of mixing increased when the larger atoms entered into the matrix of the smaller atoms, whereas it decreased when the smaller atoms were mixed into the matrix of the larger atoms. The maximum of the configurational entropy of mixing was not located at the eutectic composition in these alloys.