Comparision of Microstrucural and Morphological Studies of 40%Ni-Fe and 75%Ni-Fe Nanopowder Prepared by Mechanical Alloying

DOI : http://dx.doi.org/10.13005/msri/060117

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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 wasperformed for various time durations ranging between 2 to 100 h. Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD) and Particle Size Analyzer were used for characterization. In 40%Ni-Fe the grain size first decreases with milling till 8 h and then increases reaching the next highest value at 16 h. After 16h the grain size continuously decreases reaching the lowest value of 7.3 nm at the end of 100h of milling. In 75%Ni-Fe alloy the grain size decreases continuously with milling h reaching the value of 34 nm at 100 h of milling. It is observed from 40%Ni-Fe that the particle size decreases continuously with milling time as the fracturing forces dominate over the cold welding 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 h of milling. In 75%Ni-Fe alloy during 2 to 8 h of milling the particle size remain constant at 13.5 μm. During 32 to 64 h of milling, it is observed that the particle size remains constant at 7.5 μm. This may be due to equilibrium between the fracturing and cold welding forces in these regions of milling. The particle size decreases after 64 h and reaches the lowest value of 3 μm at 100 h of milling.

Mechanical alloying; particle size; morphological study; microstructure.