Current and emerging practices of CALPHAD toward the development of high entropy alloys and complex concentrated alloys

This work presents a critical review of the application of CALPHAD techniques in the development of high entropy alloys (HEAs) and complex concentrated alloys (CCAs). This assessment covers three major themes: thermodynamics of mixtures and stability, retrospective thermodynamics, and predictive thermodynamics. Based on statistical and thermodynamic analysis, we assess the concept of entropic stabilization. A brief description of the major accomplishments of the CALPHAD technique applied to explain the stability and microstructure of HEAs and CCAs is presented. We describe the role of CALPHAD and its integration with other design tools, such as physicochemical criteria, data mining, and optimization techniques, to accelerate the discovery of new materials. Finally, we recommend future efforts in the development of the next generation of HEAs and CCAs in connection with the design of their microstructures, with an emphasis on precipitation strengthening and twinning-induced or transformation-induced plasticity (TWIP, TRIP).