The Calculation Of Formation Dnthalpy Of Multi-Component Alloys With Miedema Theory

The thermodynamic properties of materials are very important on the point of view of science and technology. It is basic database for materials design. The theorectical prediction of thermodynamic properties for multicompont alloys attract more and more attentions due to the development of computer science and technology. In general, the thermodynamic properties of alloys can be measured experimentally. However, it is not time-consume to perform experimental measurement for multi-component alloys due to the great amount of experiments. So, the theoretical prediction and extrapolation is a significant and effective approach to obtain thermodynamic properties of multi-component alloys.A lot of method and/or model for predicting the thermodynamics properties of alloy have been proposed in the past years. Among them, Miedema theory and embedded atom method have been widely used to predict formation enthalpy of binary alloys. The formation enthalpy for most of binary alloys have been calculated by Miedema theory. The thermodynamic properties of multi-component alloys could be calculated by the geometric model, such as Chou’s model, Toop model and Ouyang’s model. The thermodynamic properties for some Cu-base, Fe-base and Al-base multi-component alloys have been predicted by the extrapolated geometric model proposed by Ouyang et al. and Miedema’s theory.In the paper, formation enthalpies of liquid ternary alloys for FeNiZr, CuAgAu, CeAgAu, NiCuAl, AuSbSn, YCuMg, AuCuSn, AlCuSn, AlCuNi NiSbSn and FeTiNi were calculated. The formation enthalpies were compared with those obtained by Toop model and experimental data. As for Al-Cu, Al-Ni, Ni-Sb, Ni-Sn system, the calculated formation enthalpies were obtained by setting the value of γ to8due to the chemical short range order of them. The present calcalations are in good agreement with the experimental data.Formation enthalpies of liquid and solid solution ternary alloys for AlCu-RE system(RE=Ce, Dy, Er, Eu, Gd, Ho, La, Lu, Nd, Pm, Pr, Sm, Tb, Tm, Yb) and AlCu-X system(X=Mg, Mn, Ni, Si, Sr, Ti, Zn, Zr) were calculated. The formation enthalpies of liquid, solid solution and intermetallic quaternary alloys for AlFeZrCe and AlFeZrNd were also calcaluted.The minimum of formation enthalpy for AlCu-RE system is locating about XRE=50at.%. It means that, the rare earth element add can enchance the stability of the alloy. The contour of formation enthalpies for AlFeZrCe and AlFeZrNd are similar, the formation enthalpy of AlFeZr-RE decreases gradually with the increase of the mole fraction of Al and Zr elements, the formation enthalpy decreases gradually with the increase of the mole fraction of the rare earth elements when the mole fraction of Al is more than50%, but the formation enthalpy increases gradually with the increase of the mole fraction of the rare earth elements when the mole fraction of Al is small.The results of formation enthalpy for ternary and quaternary alloys are in good agreement with the experimental data and other predictionds available. This indicates that the geometric model of Ouyang et al. can be used to predict the multi-component alloys due to its inclusion of interaction of constitute of alloys. It is potential approach for thermodynamic properties of multi-component alloys.