Effect of annealing on nanostructure and magnetic properties of Zr2Co11 material

•Zr–Co alloy ribbons consist of the single phase with the rhombohedral structure.•Annealing decreases structural disorder's density, thus greatly increases coercivity.•A record value (9.7 kOe) of coercivity has been achieved in annealed Zr2Co11 alloys.•Zr2Co11 has potential for fabricating rare-earth-free hard magnetic nanocomposites.

Single-phase Zr2Co11 nanomagnetic materials with high coercivity have been fabricated by melt spinning with subsequent annealing under Ar, N2, and vaccum. Annealing coarsens the grains and decreases the density of defects, leading to intergrain decoupling action and the enhancement of the magnetocrystalline anisotropy field of the hard magnetic phase. Therefore, coercivity increases 44.7% from 6.7 kOe for the as-spun to 9.7 kOe for the annealed which is the highest among Zr–Co alloys so far. The results show that the magnetic-hardening mechanism is primarily dominated by domain-wall pinning. In addition, annealing clearly increases the saturation magnetization. The above results indicate that Zr2Co11 has potential for fabricating rare-earth-free permanent-magnet nanocomposites.