Effects of Mechanical Alloying on Microstructure, Morphology and Magnetic Properties of 40%Ni-Fe Nanopowder

DOI : http://dx.doi.org/10.13005/msri/050206

Download this article as: 

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 80 and 25μm 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 is seen to decrease with milling till 8 hours and also after 16 hours. The lowest value of 7.3 nm is reached at the end of 100 hours of milling. The particle size decreases with milling time as the fracturing forces dominate over the cold welding forces during the entire period. At the end of milling the particle size does not change appreciably due to the equilibrium between the fracturing and cold welding forces. The particle size reaches the lowest value of 0.967 μm at the end of 100 hours of milling. Average coercive field reaches the maximum value of 46.68 Oe at the end of 2 hours of milling. The results show that the average remanent magnetization and the maximum permeability are also the highest after 2 hours of milling. All these coupled with low hysteresis loss will make the 40% Ni-Fe alloy after 2 hours of milling suitable for permanent magnets. Average coercive field and squareness are fairly high after 2 hours of milling and also after 100 hours of milling. Choosing the lower milling time the 40 % Ni-Fe alloy will also be suitable for magnetic storage materials after 2 hours of milling.

Mechanical alloying; particle size; morphological study