Soft magnetic properties of amorphous Fe₅₂Co₃₄Hf₇B₆Cu₁ alloy treated by pulsed magnetic field and annealing

The crystallization, microstructure, and soft magnetic properties of Fe₅₂Co₃₄Hf₇B₆Cu₁ alloy are studied. Amorphous Fe₅₂Co₃₄Hf₇B₆Cu₁ alloys are first treated by a pulsed magnetic field with a medium frequency, and then annealed at 100 °C–400 °C for 30 min in a vacuum. The rise in temperature during the treatment by a pulsed magnetic field is measured by a non-contact infrared thermometer. The soft magnetic properties of specimens are measured by a vibrating sample magnetometer (VSM). The microstructure changes of specimens are observed by a Mössbauer spectroscopy and transmission electron microscope (TEM). The results show the medium-frequency pulsating magnetic field will promote nanocrystallization of the amorphous alloy with a lower temperature rise. The nanocrystalline phase is α-Fe(Co) with bcc crystal structure, and the grain size is about 10 nm. After vacuum annealing at 100 °C for 30 min, scattering nanocrystalline phases become more uniform, the coercive force and the saturation magnetization of the specimens are 41.98 A/m and 185.15 emu/g.