Mechanism of Reduction in Grain and Particle Sizes of Nix-Fe100x Nanopowder by Mechanical Alloying

Ball milling with high energy for mechanical alloying was followed to make Ni-Fe alloy powders from elemental Ni and Fe powders having the sizes of 80 mu m (Ni) and 25 mu m (Fe). Preparations were carried out at room temperature with various duration of time ranging from 2 to 100 hours using ball milling with high energy. Analyses based on X-ray diffraction pattern and particle size analyzer were used for characterization of powders. During ball milling, it was observed that the reduction of grain size and particle size occurred in a stepped fashion. This observation indicates that the reduction in grain size and particle size occurs in a successive cyclic fashion, contrary to the expectation of concurrent reduction.