MARTENSITIC TRANSFORMATION IN SOME FERROUS ALLOYS UNDER MAGNETIC FIELD

摘要

Martensitic transformations of ferromagnetic materials are extensively influenced by a magnetic field. The transformation temperature changes, because the free energy between parent and martensite phases changes under magnetic field. In a special case, the martensite phase is induced only while a magnetic field is applied, and is transformed back to the parent phase when the magnetic field is removed. The martensite plate formed under magnetic field tends to align to the field direction. Furthermore, in some ferromagnetic shape memory alloys, a giant magnetic field-induced strain of more than 1 % appears due to rearrangement of martensite variants.