Amorphous formation and magnetic properties of Co-containing Fe-Si-B-P-Cu nanocrystalline alloys

Fe84.3-xCuxSi4B8P3Cu0.7 (x = 0, 2, 4, 6, 8, and 10 at.%) alloy ribbons were fabricated by melt spinning. Results showed that the FeCoSiBPCu alloys added with 0-10 at.% Co showed improved amorphization. The modified alloys displayed not only high thermal stability but also high heat treatment temperature in the range of 150-160 K. Compared with the other Co-containing alloys, the alloys added with 2-4 at.% Co exhibited a higher saturation magnetization (M-s) of approximately 181-194 emu/g and a lower coercive force (H-c) of approximately 10.2-12.3 A/m, thus showing improved magnetic properties in the melt-spun state. When annealed before the secondary onset crystallization temperature, all alloys crystallized a single alpha-Fe phase. After annealing at 833 K for 10 min, the alloys added with 8-10 at.% Co showed excellent soft magnetic properties, including a high M-s of 198-200 emu/g and a low H-c of 2.6-2.9 A/m.