Abstract
Decrease in the magnetostriction and increase in the magnetization with changing magnetic annealing time were observed over a temperature range 573 to 723 K for Fe-5.66–11.22 mass%Al alloys. The room-temperature maximum permeability of the alloys, cooled without magnetic field after the time-variations of magnetostriction and magnetization had ended, is higher than that of the thermally demagnetized alloys. The relaxation phenomenon is most remarkable in the Fe-7.72 mass%Al alloy; its activation energy calculated from the relation between relaxation time and magnetic annealing temperature is about 163 kJ/mol. This value is approximately equivalent to the energy required for the interdiffusion of Al and Fe atoms primarily due to the movement of vacancies in the disordered Fe–Al alloys. It seems most probable that the effect of the magnetic annealing observed in the Fe–Al alloys arises from rearrangement and fixing of magnetic domains due to relaxation of internal stress by the magnetostriction at high temperatures.
