Phase field simulation of microstructure evolution in Fe-Cr-Co alloy during thermal magnetic treatment and step aging

The evolution of modulated structures in Fe-Cr-Co alloys during isothermal aging under an external magnetic field and multiple step aging was simulated based on a phase field method. In this simulation, the magnetic configuration during the decomposition was calculated by a micromagnetic method, and the chemical Gibbs energy function was calculated by the CALPHAD approach based on the experimental equilibrium phase diagram. The calculation results provide a quantitative microstructure change directly linked to the phase diagram and demonstrate obvious microstructure difference between isothermal aging and multiple aging. The ferromagnetic precipitates elongate along the direction of the external magnetic field. The simulated evolution and microstructure are in good agreement with the experimental results.