Significantly enhanced magnetic properties of a powder of amorphous Fe70MnxMo3Cr4-6W8-10Si4-5B3-5 particles achieved by annealing treatments below the crystallization temperature

Annealing treatments below crystallization temperature were conducted on commercial Fe70Mnx Mo3Cr4-6W8-10Si4-5B3-5 (x = balance) amorphous powder. It was found that such treatment could significantly improve the soft magnetic properties of the powder especially at a higher frequency. Saturation magnetization increased to a maximum and hysteresis loop decreased to a minimum after the powder was annealed at 800K for 30 min. Magnetic force microscopy observation indicated that the size of domain structure was not changed but the phase contrast became obvious after annealing. The enhancements of soft magnetic properties were explained in terms of structural relaxation and nanocrystallization as well as the Bethe-Slater curve. Moreover, a characteristic frequency at which the a. c. susceptibility exhibits a drastic change is found and that frequency changes with the annealing treatment. (C) 2014 AIP Publishing LLC.