Article ID: MT-M2024129
Differential thermal analysis (DTA) on quenched Mn55Al45 with hcp structure (ε-phase) was performed under magnetic fields up to 15 T in order to investigate the magnetic field effects on the transformation kinetics of ε-phase. So far, the annealing of ε-phase under magnetic field indicated the acceleration of the phase transformation from the ε-phase to the metastable ferromagnetic τ-phase with L10 structure and the suppression of the decomposition into the equilibrium phase (β-phase). In this study, as the magnetic field intensity increased, the transformation temperature from ε-phase gradually decreased to the lowest value in the range from 0 to 4 T. A single exothermic peak was observed on each DTA curve, and it was found that the peak contained plural exothermic ε−τ and τ−β transformations. Activation energy of the transformation also showed the lowest value in the magnetic field range from 4 to 10 T, suggesting that the activation energy of the ε−τ transformation decreases at low magnetic field region from 0 to 4 T and the activation energy of the τ−β transformation increases at high magnetic field region from 10 to 15 T. These changes in activation energy were discussed by contribution of Zeeman energy for nucleation of the τ-phase in the ε-matrix and that of β-phase from the τ-phase.
