用改进的CSA法计算多元固溶体混合熵(英文)

Improved cluster-site approximation for the entropy of mixing in multicomponent solid solutions

:CSA法在估算多元固溶体的混合熵方面 ,有比CVM法计算简单的优点 所以 ,CSA法特别适合于利用实验数据优化计算多元合金体系的相图 采用相同的能量参数及结构 ,比较了用蒙特卡罗 (MC)法、CVM法及CSA法计算的结果 ,由此可知 ,由于CSA法引入了 1个参数 ,增强了实用性 ,计算得到的Cu Au相图与用蒙特卡罗 (MC)

Although not as soundly based,the cluster site approximation (CSA) has the considerable advantage of computational simplicity over the cluster variation method (CVM) for the evaluation of mixing entropies in multicomponent solid solutions.The CSA is thus particularly suitable for the calculation of technologically important phase diagrams of multicomponent alloys,a task which necessarily depends on the optimization of the models′ energy parameters with the available experimental data for the constituent binary and ternary systems.Comparison of results obtained by Monte Carlo (MC) simulations for the same energy parameters with those obtained by the CVM and CSA for the tetrahedron approximation for fcc alloy shows them to be of comparable accuracy the CVM finds the solution to be more random whereas the original CSA (due to Yang and Li) finds the solution to be less random when compared with the MC results.It it shown how the CSA can be improved by the introduction of a single correction parameter.Some CSA calculated prototype binary phase diagrams which agree very well with those obtained from MC calculations are presented together with two phase diagrams for the Cu Au system which can be compared with similar diagrams previously calculated using the CVM.It is not suggested that the modified CAS should replace the use of large clusters in the CVM for (first principles) phase diagram calculations for binary systems