EFFECTS OF STATIC MAGNETIC-FIELD AND HYDROSTATIC-PRESSURE ON THE ISOTHERMAL MARTENSITIC-TRANSFORMATION IN AN FE-NI-MN ALLOY

The effects of static magnetic fields and hydrostatic pressures on the isothermal martensitic transformation, whose nose temperature is about 150 K, in an Fe-24.9Ni-3.9Mn alloy (mass%) have been studied by examining the TTT diagrams under those external forces. As a result, it was clarified that the static magnetic fields made the nose temperature lower and the incubation time shorter than those under no external magnetic field, while the hydrostatic pressures made the nose temperature higher and the incubation time longer than those under no external hydrostatic pressure. The shifts of nose temperature and incubation time increased with increasing the strength of those external forces. These results were well explained by the new phenomenological theory, which was previously constructed by the present authors and gives a unified explanation for the isothermal and athermal kinetics of martensitic transformations, suggesting that the theory was further confirmed to be appropriate.