aRajalakshmi Engineering College, Thandalam, India.
bMadras Institute of Technology, Chromepet, India.
cIndian Institute of Technology, Kanpur, India.
Mechanical alloying through high energy ball milling was used to produce Ni-Fe alloy powders starting from elemental Ni and Fe powders of average particle size 79 and 25 μm respectively. High energy planetary ball milling at room temperature was performed for various time durations ranging between 2 to 100 hours. Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD) Particle Size Analyzer and Vibrating Sample Magneto Meter were used for characterization. The grain size decreases rapidly at the beginning of milling and after 64 hours of milling the change in grain size is not appreciable. The change is only from 25.5 to 22 nm only. It is observed that the particle size generally decreases with milling time and between 8 hours and 16 hours of milling the particle size does not change appreciably showing that equilibrium is reached between the rate of welding and the rate of fracturing. After 16 hours the particle size decreases continuously reaching the lowest value of approximately 3 μm at 100 hours. After 2 hours of milling the alloy shows high retentively, highest coercive field and maximum permeability. This makes it suitable for permanent magnets. After 64 hours of milling the alloy has lowest saturation field and low hysteresis loss and high permeability. This allows their applications for soft magnetic materials.
Mechanical alloying, particle size, morphological study
