Abstract
The thermodynamic extremal principle incorporating the constraints from both fluxes and forces pro-posed in part Ⅰ was applied to isothermal diffusion in multi-principal element alloys(MPEAs)to propose the so-called double-constraint model.The model cannot reduce physically to the previous model con-sidering only the constraint from fluxes(i.e.,the single-constraint model)but in special cases reduces to Fick's law and Darken's equation,showing its reliability.Similar to the previous pair-wise model and single-constraint model,the solutes and solvent do not need to be defined in advance in the double-constraint model and the model can be also applied directly to diffusion in MPEAs.Applications to isothermal diffusion in CoCrFeMnNi pseudo-binary diffusion couple and CoCrFeNi,CoCrFeMnNi body-diagonal diffusion couples showed that the present double-constraint model overall predicted better the experimental results than the previous single-constraint model,indicating again the necessity to consider the constraints from both fluxes and forces in the phenomenological theory of Onsager.
基金项目
Natural Science Foundation of China(51975474)
Natural Science Foundation of China(52304414)
Fundamental Research Funds for the Central Universities(3102019JC001)
NETL
NSTL
万方数据