Short Technical Note: Characterization of mechanically alloyed Fe100-xSix and Fe83.5Si13.5Nb3 nanocrystalline powders

In present research, nanocrystalline Fe100-xSix (x = 6.5, 10, 13.5, 20 and 25 at.%) and Fe83.5Si13.5Nb3 alloy powders were prepared by mechanical alloying using high-energy ball milling. The resulting powders mainly consist of micron-sized particles with an average grain size of less than 20 nm. According to the XRD test results, by increasing the milling time and/or the Si content the lattice parameter decreases and the internal microstrain increases. In addition, the specific saturation magnetization diminishes as Si content increases. The coercive forces of the as-milled nanocrystalline powders are much higher than those of corresponding Fe-Si bulk alloys with a minimum at 13.5 at.% Si. The presence of Nb retards the crystallite coarsening during annealing but adversely affects the magnetic properties. Annealing of milled powders caused the coercive force to reduce slightly due to reduction of internal strains.