화학공학소재연구정보센터
Materials Science Forum, Vol.394-3, 531-536, 2001
Giant magnetostriction in Fe3Pt and FePd ferromagnetic shape-memory alloys
Magnetostriction has been investigated for ordered Fe3Pt and disordered Fe-31.2Pd(at.%) alloys exhibiting a martensitic transformation from a cubic phase to a tetragonal phase at 85K and 225K, respectively. The tetragonality of Fe3Pt at 14K is 0.944(6), and that of Fe-31.2Pd(at.%) at 77K is 0.940(3). In Fe3Pt, whose easy axis is the c-axis in martensite state, a large contraction of about 2.3% appears in [001] direction at 4.2 K by applying the magnetic field along [001] direction, and a part of this contraction (0.6%) recovers as the field is removed. This value of recoverable magnetostriction is more than three times as large as that of Terfenol-D. In Fe-31.2Pd(at.%), whose easy axis is the a-axis in martensite state, a large expansion of about 3% appears in [100] direction at 77 K by applying the magnetic field along [100] direction. This strain is nearly the same as the value that is expected from the perfect conversion to the preferred variants.