ROLE OF MICROSTRUCTURE AND DOMAIN STRUCTURE ON THE SOFT MAGNETIC PROPERTIES OF MAGNETIC FIELD ANNEALED Fe_89-xZr₁₁B_x ALLOYS

We report the evolution of microstructure, domain structure, and soft magnetic properties of amorphous and nanocrystalline Fe_89-xZr₁₁B_x(x = 0 - 10) alloys. High-resolution electron microscopy observations reveal that the annealed alloys exhibit a two-phase microstructure. Addition of B enhances the ferromagnetic properties of Fe–Zr amorphous phase in the two-phase structured microstructure, resulting in good soft magnetic properties. Large-sized domains with smooth domain walls are observed in the alloys annealed below 873 K, which exhibit excellent magnetic softness. On the other hand, in the alloys annealed above 873 K, small-sized domains with irregular domain walls and domain wall pinning by Fe–Zr compound are seen. The soft magnetic properties in Fe–Zr–B alloys not only depend on mean grain size, but also on the strength of the intergranular magnetic coupling and structural inhomogeneities.