Abstract
In the present work, morphological and structural changes induced by 18 MeV He+ ions in pure iron (Fe) matrix have been reported. Pure Fe samples were irradiated by 18 MeV He+ ions at different fluences ranging from 1 × 1013 ions cm−2 to 1 × 1016 ions cm−2 at 300 K under vacuum by using Cyclotron Accelerator. The surface morphology of irradiated samples was studied through field emission scanning electron microscopy (FESEM). The FESEM results revealed the formation and growth of micro-size pits, cavities, voids and incoherent structures at different irradiation fluences. The formation of these pits/incoherent structures was attributed to the melting, re-deposition and sputtering of the irradiated surface. The small size Fe particles were ejected out from the sample's surface at lower fluence (1 × 1013 ions cm−2) which were then transformed into large size pits/craters at higher fluence (1 × 1016 ions cm−2). The existence of these Fe particles was confirmed through energy dispersive x-ray spectroscopy (EDS). The structural analysis by x-ray diffraction (XRD) indicated a variation in intensities of Fe diffraction peaks, peaks shifting and broadening that became more pronounced with increase of the irradiation fluence. These structural changes were attributed to the accumulation of irradiation induced stresses inside the Fe matrix.