Magnetic field effects on crystallization of iron-based amorphous alloys

The crystallization behavior of iron-based amorphous alloys has been investigated in high magnetic fields by differential thermal analysis (DTA) and magnetization measurements. DTA of FeSiB amorphous alloys showed that the exothermic peaks shift toward higher temperature under high magnetic fields. At 10 T, peak temperatures of the crystallizations increased approximately 3K, compared with those at a zero magnetic field. Such a variation in the crystallization peak was not observed in the Fe-B-Nb-Y bulk metallic glass (BMG). In the temperature dependence of the saturation magnetization for the Fe-Si-B amorphous alloy, the sudden increase of the magnetization was found at the crystallization temperatures. The magnetization of Fe-Si-B increased 56 and 40Am² kg^-1 at the first and second crystallization temperatures, respectively. This magnetization behavior indicates the magnetic transition from the paramagnetic to the ferromagnetic state, accompanying the crystallization, whereas there is only a slight increase in magnetization at the crystallization temperature in FeBNbY BMG. The effect of magnetic field on the crystallization peak as observed from DTA is related to the increase in the magnetization at the crystallization temperature.