Synthesis of Fe-Si-B-Mn-based nanocrystalline magnetic alloys with large coercivity by high energy ball milling.

Alloys of Fe-Si-B with varying compositions of Mn were prepared using high energy planetary ball mill for maximum duration of 120 h. X-ray diffraction (XRD) analysis suggests that Si gets mostly dissolved into Fe after 80 h of milling for all compositions. The residual Si was found to form an intermetallic FeSi. The dissolution was further confirmed from the field emission scanning electron microscopy/energy dispersive X-ray analysis (FE-SEM/EDX). With increased milling time, the lattice parameter and lattice strain are found to increase. However, the crystallite size decreases from micrometer (75-95 μm) to nanometer (10-20 nm). Mössbauer spectra analysis suggests the presence of essentially ferromagnetic phases with small percentage of super paramagnetic phase in the system. The saturation magnetization ( M), remanance ( M) and coercivity ( H) values for Fe-0Mn sample after 120 h of milling were 96.4 Am/kg, 11.5 Am/kg and 12.42 k Am, respectively. However, for Fe-10Mn-5Cu sample the M, H and M values were found to be 101.9 Am/kg, 10.98 kA/m and 12.4 Am/kg, respectively. The higher value of magnetization could be attributed to the favourable coupling between Mn and Cu. [ABSTRACT FROM AUTHOR]