Crystallization Phases and Crystallization Saturation Magnetization Under Different Annealing Ways in Fe-Rich Fe-B/SiBP-Cu-Hf Alloys

Entirely amorphous ribbons are successfully fabricated by adding Hf for half Cu in Fe-rich Fe86B13Cu1-xHfx and Fe85Si2B8P4Cu1-yHfy alloys, which indicates that Hf plays a positive role in promoting the glass forming ability. Differential scanning calorimetry curves of both Fe86B13Cu0.5Hf0.5 and Fe85Si2B8P4Cu0.5Hf0.5 amorphous ribbons show two obvious exothermic peaks, which implies the alloys will need a two-step crystallization before reaching the stable state in the subsequent crystallization process. During the normal annealing, alpha-Fe grains are formed initially at 623 K, later the Fe85Si2B8P4Cu0.5Hf0.5 alloy starts to form Fe-(B, P) compounds at 723 K, while the Fe86B13Cu0.5Hf0.5 alloy only begins to precipitate Fe-B compounds at a relatively higher temperature of 798 K. However, for flashing annealing, both the amorphous ribbons only start the initial crystallization of alpha-Fe phase as the annealing temperature less than T-x2(the onset temperature of the secondary crystallization). M-s (saturation magnetization) values of both Fe86B13Cu0.5Hf0.5 and Fe85Si2B8P4Cu0.5Hf0.5 ribbons show an increasing trend after annealing and reach a maximum of about 206.3 and 212.2 emu/g by normal annealing and 208.2 and 216.2 emu/g by flashing annealing, respectively. Therefore, crystallization phases and M-s are easier and more effective to be adjusted by flash annealing, and further, the ribbons with uniform alpha-Fe phase show excellent soft magnetic properties.