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

Abstract

Substituting Fe with Co in Fe-based alloys to adjust the composition and optimize properties is a hot topic. Amorphous Fe_84-xCo_xZr₇B₉ (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  Fe_84-xCo_xZr₇B₉ (x=0, 7, 14, 21) alloys, and the second region corresponds to the  Fe_84-xCo_xZr₇B₉ (x=28, 35, 42)  alloys.  There  are  four  exothermic  peaks  for  Fe_84-xCo_xZr₇B₉ (x=0, 7, 14, 21) alloys, and there are three crystallization exothermic peaks for Fe_84-xCo_xZr₇B₉ (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 (V_cry) 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 M_s 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  M_s  values of annealed alloys are  greater  than  those  of  as-quenched alloys. The coercivity H_c values of annealed alloys are lower than those of  as-quenched alloys.  For Fe_84-xCo_xZr₇B₉ (x=0, 7, 14, 21) alloys, the higher the Co content, the higher the difference between the H_c values of as-quenched and annealed alloys. For Fe_84-xCo_xZr₇B₉ (x=28, 35, 42) alloys, the difference between the H_c values of as-quenched and annealed alloys is small.