حسین اسکندری

In this study, microstructural evolution, mechanism of nanostructure formation and magnetic behavior of nanostructured Fe50Co30Ni20 alloy prepared by mechanical alloying (MA) were investigated. The structural and magnetic properties have been investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and vibrating sample magnetometer (VSM). X-ray diffraction showed that during mechanical alloying process the Fe-based solid solution with BCC lattice was formed after 16 h of milling. The powders exhibited a minimum crystallite size of ~ 18.7 nm and lattice parameter of ~ 0.2848 nm after 32 h. Moreover, after milling time of 32 h, the lattice strain and volume fraction of grain boundary reaches to about 0.43 % and 4.48 %. Grain size refinement enhances magnetization saturation to about 136 emu/g and decreases coercivity to approximately 49 Oe for milling time 4 and 8 h, respectively. Heat treatment of the samples milled at 32 and 48 h demonstrated the crystalline constituent elements and Fe3O4, FeNi3 and Co crystalline phases. In addition, heat treatment at 450 ?C for milling times 32 and 48 h led to increase in saturation magnetization and coercivity. The annealed samples at 650 ?C exhibited a remarkable increase and decrease in saturation magnetization and coercivity, respectively. Furthermore, thermal treatment resulted in increasingofcrystallite size and decreasing oflattice strains.