The effects of rapid annealing on nanocrystallization and soft magnetic properties of Fe83-xNi2B15Cux alloys

In this work, the effects of rapid annealing on the nanocrystallization behavior and magnetic properties of Fe_83-xNi₂B₁₅Cu_x (x = 0, 0.6, 0.9, 1.1, 1.3) alloy were systematically investigated. Additionally, the influences of Cu addition on structure, thermal stability, crystallization behavior and soft magnetic properties of Fe_83-xNi₂B₁₅Cu_x alloys were also studied in detail. It was found that a fully amorphous structure was formed in the as-spun ribbons. Analysis of thermal properties showed that with the increase of Cu content, the onset temperature of the first crystallization peak (T_x1) decreased sharply for the as-spun Fe_83-xNi₂B₁₅Cu_x alloy ribbon and a large ΔT (ΔT = T_x2 -T_x1) of 105 K was obtained in Cu1.3 alloy which facilitated the precipitation of α-Fe phase. The H_c results from annealed samples indicated that soft magnetic properties can be optimized using rapid annealing treatment primarily due to the grain refinement caused by the large overheating and short duration time during annealing process. With appropriate addition of Cu element and rapid annealing treatment, uniform and dense microstructure consisting α-Fe grains with an average size distribution around 15 nm within amorphous matrix was achieved in rapid annealed Cu1.1 alloy, leading to optimized soft magnetic properties with B_s of 1.85 T and H_c of 4.3 A/m.