Magnetic properties of nanostructured MuMetal (Ni0.77Fe0.16Cu0.05Cr0.02)

Abstract

Nickel-Iron (Ni-Fe) based alloys exhibit low coercivity, high permeability and high saturation magnetization. They are of interest for their application as soft magnetic materials. Reducing their particles sizes to nano-scale is believed to enhance this properties. As such, nanocrystalline magnetic materials have wide ranging applications in magnetic recording devices, high power magnets, biomedical sciences and medical diagnostics.

In this study, nanocrystalline Mumetal (Ni0.77Fe0.16Cu0.05Cr0.02 alloy) powders were synthesized using planetary high-energy ball milling under argon atmosphere. The X-ray diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM) were employed to study the alloy formation and corresponding magnetic properties as a function of milling time, ranging from 0h to 96h.

Complete formation of alloy phase, γ- (Fe, Ni, Cu, Cr) was observed after 12h of milling. The powder particles were refined to spherical shapes with increasing milling. In addition, decreasing crystallite size and increasing lattice parameter corresponded with increasing milling time. Likewise, results obtained from the VSM suggest that with increasing milling time, saturation magnetization increases and coercivity decreases.