Phase field simulations on domain switching-induced toughening in ferromagnetic materials

A real-space phase field model is employed to investigate the domain switching-induced shielding or anti-shielding of a crack in ferromagnetic materials with single and multi-domain states. Phase field simulations demonstrate that magnetization switching takes place from the crack tip due to the highly concentrated stress in a ferromagnetic thin plate with a stationary crack. Based on the stress obtained from phase field simulations, the crack-tip stress intensity factors (SIFs) are calculated by linear extrapolation in the ferromagnetic thin plate subjected to different values of mechanical loads. The calculation results indicate that domain switching decreases the crack-tip stress intensity factors, resulting in domain-switching toughening in ferromagnetic materials. Furthermore, the domain switching in the multi-domain ferromagnetic plate induces a much larger decrease of stress intensity factor than that in the single-domain one, which suggests that engineering magnetic domains leads to the design of tougher ferromagnetic materials.