Phase field study of grain boundary migration and preferential growth in non-magnetic materials under magnetic field

This work reports a phase field model to enable a profound insight into the grain boundary (GB) migration of non-magnetic materials based on Bi bicrystals under a magnetic field. Simulation results on GB migration velocity agree well with the experimental results, and the velocity increases linearly with the square of the magnetic strength. It is also found that GB migration direction is affected by the magnetic field direction, and grain with c-axis parallel to the magnetic field direction grows preferentially at the expense of the grain with c-axis perpendicular to the magnetic field direction. It is revealed that the preferential grain growth is induced by the difference in magnetic free energy density of the grains with different orientations.