Fabrication of alloys in the solid state via mechanical alloying (MA) process has been studied by earlier researchers. The effects of milling time and impact force, defined as the ball-to-powder weight ratio (BPR), on the elemental diffusion during synthesis of nanostructured Fe-50at.%Cu alloy via MA process were evaluated in the current work. X-ray diffraction patterns revealed that increasing the milling time and impact force give rise to increasing the micro-strain, lattice parameter and decreasing the crystallite size during the MA process. Furthermore, scanning electron microscopy (SEM) was utilized not only for evaluating the microstructure of the milled powder particles but also for proving this claim that during MA process, the mutual diffusion of Cu and Fe has occurred. The interpretation of data resulted have been discussed in details.