Prediction of phase structures of solid solutions for high entropy alloys

Abstract

In this paper, we have developed new parameters to simultaneously assess phase constitutions of the solid solutions in 124 HEA systems. According to the second law of thermodynamics, the lower the Gibbs free energy of a certain state of the system, the more stable the state. As such, a thermodynamic parameter ΔGF−B was presented to estimate the propensity for a material system to form BCC or FCC solid solutions depending on the comparison between their Gibbs free energies in different states. In addition, it is found that the presence of B2 and L12 ordered phases also affects the accuracy of the prediction, hence we classified the constituent elements of ordered phases into two categories whose content ratio is taken as a completely new ratio parameter ∅ to rapidly predict the structures of solid solution phases. This model displays a good correlation with the experiments and reveals the various factors affecting the structures of the solid solutions from the Gibbs free energies and the ordered phases, which is crucial for the alloy design and controllable mechanical behavior of HEAs.

Keywords

• High entropy alloys
• Thermodynamic stability
• Multi-component alloys
• BCC phase
• FCC phase