Effect of magnetic ordering on the spinodal decomposition of the Fe-Cr system: A GPU-accelerated phase-field study

Abstract

This study aims to investigate the effect of magnetic ordering on spinodal decomposition behavior in the Fe-Cr system using graphics processing unit(GPU) parallelization. We modify the CALPHAD-type free energy to remove its critical behavior near the paramagnetic-ferromagnetic transition. We solve the Cahn-Hilliard equation using a semi-implicit Fourier spectral method, parallelizing the code to run on a GPU via compute unified device architecture and OpenMP. We find that the GPU parallelization gives better performance than that of OpenMP when using fast Fourier transforms to solve the Cahn-Hilliard equation. We conduct nine sets of simulations to examine the effect of magnetic ordering, and we found that it alters the interfacial energy between Cr-rich and Cr-depleted phases, equilibrium concentrations, and energy barrier for phase transformations. We apply a phase-field method to examine in detail how these changes affect the microstructural evolution, quantitatively evaluating the microstructures obtained in terms of the precipitate number density, average phase area, and phase boundary density along certain auxiliary lines to analyze the effects of magnetic ordering.