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 Fe
₈₆
B
₁₃
Cu
_1-x
Hf
_x
and Fe
₈₅
Si
₂
B
₈
P
₄
Cu
_1-y
Hf
_y
alloys, which indicates that Hf plays a positive role in promoting the glass forming ability. Differential scanning calorimetry curves of both Fe
₈₆
B
₁₃
Cu
_0.5
Hf
_0.5
and Fe
₈₅
Si
₂
B
₈
P
₄
Cu
_0.5
Hf
_0.5
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, α-Fe grains are formed initially at 623 K, later the Fe
₈₅
Si
₂
B
₈
P
₄
Cu
_0.5
Hf
_0.5
alloy starts to form Fe-(B, P) compounds at 723 K, while the Fe
₈₆
B
₁₃
Cu
_0.5
Hf
_0.5
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 α-Fe phase as the annealing temperature less than T
_x2
(the onset temperature of the secondary crystallization). Ms (saturation magnetization) values of both Fe
₈₆
B
₁₃
Cu
_0.5
Hf
_0.5
and Fe
₈₅
Si
₂
B
₈
P
₄
Cu
_0.5
Hf
_0.5
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 Ms are easier and more effective to be adjusted by flash annealing, and further, the ribbons with uniform α-Fe phase show excellent soft magnetic properties.