The Effect of Hf Substituting for Cu on the Glass-Forming Ability, Crystallization Behavior, and Saturation Magnetization in Fe{sub 85}Si{sub 2}B{sub 8}P{sub 4}Cu{sub 1−x}Hf{sub x} Alloys

The effect of Hf substituting for Cu on the glass-forming ability (GFA), crystallization behavior, and saturation magnetization (M{sub s}) in Fe-rich Fe{sub 85}Si{sub 2}B{sub 8}P{sub 4}Cu{sub 1−x}Hf{sub x} alloys has been investigated. The result shows that the addition of Hf plays a positive role in improving GFA, and the Fe{sub 85}Si{sub 2}B{sub 8}P{sub 4}Cu{sub 0.5}Hf{sub 0.5} alloy ribbon shows an entirely amorphous structure. Both the ribbons of Fe{sub 85}Si{sub 2}B{sub 8}P{sub 4}Cu{sub 1} and Fe{sub 85}Si{sub 2}B{sub 8}P{sub 4}Cu{sub 0.5}Hf{sub 0.5} have two obviously exothermic crystallization peaks, and the addition of Hf improves the onset temperatures of both first and second crystallization peaks, and leads to the improvement of the thermal stability of the amorphous alloys. For the Fe{sub 85}Si{sub 2}B{sub 8}P{sub 4}Cu{sub 0.5}Hf{sub 0.5} ribbon, after annealing at 623 K, crystallization seeds with sizes of 2–4 nm are found and the initial crystallization has occurred; as the annealing temperature is increased to 723 and 823 K, the size distribution of most of the grains is about 20 nm and bigger than 20 nm, respectively. The M{sub s} of the Fe{sub 85}Si{sub 2}B{sub 8}P{sub 4}Cu{sub 0.5}Hf{sub 0.5} ribbon is about 154 emu/g, which is obviously lower than 205 emu/g of the Fe{sub 85}Si{sub 2}B{sub 8}P{sub 4}Cu{sub 1} ribbon. However, after annealing at 723 K, the M{sub s} increases to 212 emu/g for the former alloy. The newly developed amorphous/nanocrystalline Fe-Si-B-P-Cu-Hf alloy with excellent soft magnetic properties shows a potential application for substituting partial Si steels.