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 alpha-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 gamma-Ni and bcc-Fe(Cu), corroborating the calorimetric and thermomagnetic analysis. The coercivities (H-C)of powders improved with an increase in mill time. However, the H-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.