Phase-field study of elastic effects on precipitate evolution in (Al)0.05CrFeNi

Abstract

We introduce a new approach to include for high and medium entropy alloys, stress effects in a Phase-field model (PFM). The approach is applied to simulate the evolution of two-phase BCC/FCC microstructures of AlCrFeNi alloys, combining phase-field method with CALPHAD data and DFT (Density Functional Theory) calculations. The composition dependent Gibbs energies and diffusion mobilities of the BCC and FCC phase as a vital input for simulating real alloys into the PFM are calculated from the Thermo-Calc TCHEA2 and MOBHEA2 databases. The special quasirandom structures (SQS) method was used to obtain the complex multicomponent lattice structures and compute with DFT the elastic properties of the BCC and FCC phases. It is found that elastic stresses emerging due to a difference in eigenstrain between the BCC and FCC phases during a phase transformation have a significant effect on the precipitate formation. The effect of the eigenstrain induced elastic stress on the BCC precipitate shape, size and the equilibrium concentrations in the two phases are quantitatively studied. The PFM presented is one of the first attempts to simulate elastic effects on high entropy alloys(HEAs) microstructures. This work contributes to the understanding of the mechanisms of phase transformation and microstructure evolution in HEAs.