利用短程序改进Al-Cu熔体的热力学模型

IMPROVEMENT OF THERMODYNAMIC MODEL OF LIQUID PHASE BY SRO IN Al-Cu ALLOY

将Al-Cu熔体中的缔合物AlCu_3以短程序的形式引入置换溶液模型中,提出了一个Redlich-Kister多项式表示的缔合溶液模型,可以直接用于Thermo—Calc相图计算软件,并用这个模型改进了Al-Cu合金体系中液相的热力学描述,计算了Al-Cu熔体混合焓、固相线和平衡分凝因数,结果表明,本模型比目前广泛应用的Saunders模型能给出更好的结果,而且适用于Mg-Sn和In—Sb等二元合金体系液相的热力学描述。

Melt structure and its influence on solidification behaviors are a fundamental problem in the field of materials science. The AlCu3 associate in Al-Cu melt is incorporated into the classic substitution model as kind of short range order (SRO), and a Redlich-Kister polynomial-described associated solution model is developed to deal with the phase calculation by Thermo-Calc. The model is applied to improve the thermodynamic description of the liquid phase in the Al-Cu binary alloy. The enthalpy of mixing, solidus and equilibrium partition coefficient are calculated in several binary alloys. It is found that the present model offers more exact description than Saunders's model and is also proved to be suitable to other binary alloys, for example, Mg-Sn and In-Sb alloys.