Microstructure versus magnetic properties correlations in melt-spun Hf-Zr-Co-Fe-B alloys: role of thermal treatment

Effect of annealing on magnetic property-structure/microstructure correlation in nanostructured ribbons of a rare-earth-free Hf_1.5Zr_0.5Co₁₀FeB alloy has been reported in the present study. Melt-spinning of the arc melted alloy was employed to obtain the ribbons. The compositional, structural and magnetic measurements demonstrate that under optimized annealing conditions, the magnetically hard phases Hf₂Co₁₁B and ZrCo_5.1 appear as the dominant ones, while the magnetically soft phases Zr₆Co₂₃ and cubic Co appear as minor phase. The optimally annealed ribbons show promising values for characteristic magnetic parameters such as the saturation magnetization M_s ∼ 76.7 emu g⁻¹, intrinsic coercivity _iH_c ∼ 2.4 kOe and magnetic energy product (BH)_max ∼ 4 MGOe. Processing steps like magnetic alignment and magnetization would further improve the characteristic parameters. (paper)