Mechanism of high magnetic field effect on the D03-L12 phase transition in Fe-Ga alloys

The effect of a high magnetic field (HMF) on phase transition and microstructure formation in Fe-Ga alloys with a Ga concentration of about 25 at.% has been investigated using experimental research and ab initio modeling. We found that the HMF of 25 T significantly accelerates the D03 to L12 transformation in the hyperstoichiometric Fe-27 %Ga alloy upon isothermal annealing at 475 °C. At the same time, the field has little effect on the transformation in the hypostoichiometric Fe-24 %Ga alloy. We have found that HMF does affect the kinetics of the transformation rather than the energy of the phases. We have shown that the effect of HMF is mainly associated with the ferromagnetic ordering of magnetic moments, which leads to lattice instability of the D03 phase and enhancement of the D03 → L12 transition due to the initiation of the barrierless mechanism.