Effect of hydrogen reduction on microstructure and magnetic properties of mechanochemically synthesized Fe–16.5Ni–16.5Co nano-powder

Most recent findings on structural and magnetic properties of Fe–Ni–Co nano-powders produced by mechanical alloying and subsequent low-temperature hydrogen reduction are presented in this paper. At 300 rpm, with ball to powder weight ratio of 20, single phase nickel–cobalt ferrite is mechanically synthesized for 50 h. The as-milled powder is then subjected to 1 h hydrogen reduction at 700 °C. Hydrogen reduction results in the formation of Fe–16.5%Ni–16.5%Co nano-powders. The phases of the powders are identified by X-ray diffraction (XRD) utilizing Cu Kα radiation. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) are used to study the morphology and the average size of the nano-powder particles. Chemical analysis of the phases present in the reduced sample is determined by electron dispersive spectrometry (EDS). The magnetic properties of the powders are measured by a vibration sample magnetometer (VSM). Results indicate a noticeable change in the magnetic properties of the samples due to Ni0.5Co0.5Fe2O4 compositional change into Fe–16.5Ni–16.5Co nano-powder.