Influence of Fe and Co Content on Crystallization and Magnetic Property of FeZrB Alloys

Substituting Fe with Co in Fe-based alloys to adjust the composition and optimize properties is a hot topic. Amorphous Fe84-xCoxZr7B9 (x=0, 7, 14, 21, 28, 35, 42) ribbons were prepared and annealed at their first exothermic peak temperature. The crystallization and magnetic properties of the alloys can be divided into two regions. The first region corresponds to the Fe84-xCoxZr7B9 (x=0, 7, 14, 21) alloys, and the second region corresponds to the Fe84-xCoxZr7B9 (x=28, 35, 42) alloys. There are four exothermic peaks for Fe84-xCoxZr7B9 (x=0, 7, 14, 21) alloys, and there are three crystallization exothermic peaks for Fe84-xCoxZr7B9 (x=28, 35, 42) alloys during crystallization. Only a single phase precipitates from the amorphous matrix for all alloys after annealing. With the increase in Co content, the lattice constant first increases up to 21 at.% Co and then decreases. The crystallization volume fraction (Vcry) and the grain size (D) continue to decrease. When the Co content is 21 at.%, there is little change in Co concentration between the nanocrystal and the remaining amorphous matrix. When the Co content is 42 at.%, the Fe content in the remaining amorphous matrix is significantly less than that in the nanocrystal, and the Co content in the remaining amorphous matrix is slightly higher than that in the nanocrystal. The content of Fe in the nanocrystal is higher than that of Co in the nanocrystal. The specific saturation magnetization Ms of as-quenched alloys and annealed alloys increases sharply up to 28 at.% Co and then decreases with a further increase in the Co content. The Ms values of annealed alloys are greater than those of as-quenched alloys. The coercivity Hc values of annealed alloys are lower than those of as-quenched alloys. For Fe84-xCoxZr7B9 (x=0, 7, 14, 21) alloys, the higher the Co content, the higher the difference between the Hc values of as-quenched and annealed alloys. For Fe84-xCoxZr7B9 (x=28, 35, 42) alloys, the difference between the Hc values of as-quenched and annealed alloys is small.