Crystallization behavior and magnetic properties of melt-spun Prx(Fe0.8Co0.2)94-xB6 alloys

The influence of Pr content on the crystallization behavior of amorphous Pr-x(Fe0.8Co0.2)(94-x)B-6 (x = 12, 10, 9, 8) melt-spun ribbons and the magnetic properties following annealing have been systematically investigated. The results show that, depending on the Pr content, the phase evolution of the ribbons during crystallization occurs via different sequences. The optimal annealing conditions required rapid heating through or beyond the temperatures for the final transformation stage. For x = 12 ribbons, very good second-quadrant loop shape and magnetic property combinations (H-i(c) = 755 kA/m, (BH)(max) = 160 kJ/m(3)), though somewhat lower than those obtained by directly quenching to the nanocrystalline state, were obtained after optimal annealing. However, for the substoichiometric alloys (x = 10, 9, 8), the loop shapes and magnetic properties for optimally annealed ribbons (H-i(c) = 270 - 400 kA/m, (BH)(max) = 70 - 120 kJ/m(3)) were inferior to their directly quenched counterparts because of lower nucleation frequencies and, thus, coarser grain structures.