Evolution of microstructural and magnetic properties of mechanically alloyed Fe80 − xNi20Six nanostructured powders

The Fe80 − xNi20Six (x = 0, 5, and 10) nanocrystalline soft magnetic powders were successfully prepared via mechanical alloying (MA) route in a planetary ball mill at different milling times. The evolution of the microstructure, phase analysis, and magnetic properties during the milling process was studied using scanning electron microscopy (SEM), X-ray diffraction analysis (XRD), and a vibrating sample magnetometer (VSM). SEM observations indicated that different morphologies were obtained during the MA stages. XRD results showed that an α–(Fe (Ni–Si)) solid solution was formed after 10 h of MA and an estimated crystallite size for the Fe80Ni20 alloy after 36 h of MA was about 14 nm, which this size was reduced to about 6 nm after the addition of 10 at.% Si. An increase in lattice strain was observed by increasing the milling time and Si concentration. The VSM analysis indicated that a higher amount of Si would lead to lower values of saturation magnetization. In addition, coercivity increased during MA, reaching a maximum at 10 h of MA, and finally decreased with further MA times. This latter effect could be attributed to the effect of very fine crystallite size, obtained after prolonged milling.