Influence of Milling Time on the Microstructure and Soft-Magnetic Properties of Nanocrystalline Fe₇₂Ni₈Co₈Zr₇B₄Cu₁

The effect of milling time on the nanostructure, thermal stability, thermomagnetic, and soft-magnetic properties of Fe₇₂Ni₈Co₈Zr₇B₄Cu₁ (at.%) upon mechanical alloying up to 72 h have been investigated. X-ray diffraction pattern of the milled powders predominately consists of peaks corresponding to the bcc α-Fe phase. The electron diffraction studies of the 72 h milled powder exhibited an equidistant ring pattern superimposed on a diffuse halo pointing the presence of both nanocrystalline and amorphous phases. After heat treatment, the 60 h milled powder showed the additional diffraction peaks of γ-Ni and bcc-Fe(Cu), corroborating the calorimetric and thermomagnetic analysis. The coercivities ( \({H}_{{\text{C}}}\) $H_{\text{C}}$ ) of powders improved with an increase in mill time. However, the \({H}_{{\text{C}}}\) $H_{\text{C}}$ of ball-milled powders was relatively high due to high lattice strain, particle surface roughness, as well as the shape and surface anisotropy of the powder particles.