| dc.description.abstract |
Swift heavy ion induced changes in microstructure and surface morphology of vapor deposited Fe–Ni
based metallic glass thin films have been investigated by using atomic force microscopy, X-ray diffraction
and transmission electron microscopy. Ion beam irradiation was carried out at room temperature with
103 MeV Au9+ beam with fluences ranging from 3 1011 to 3 1013 ions/cm2. The atomic force microscopy
images were subjected to power spectral density analysis and roughness analysis using an image
analysis software. Clusters were found in the image of as-deposited samples, which indicates that the
film growth is dominated by the island growth mode. As-deposited films were amorphous as evidenced
from X-ray diffraction; however, high resolution transmission electron microscopy measurements
revealed a short range atomic order in the samples with crystallites of size around 3 nm embedded in
an amorphous matrix. X-ray diffraction pattern of the as-deposited films after irradiation does not show
any appreciable changes, indicating that the passage of swift heavy ions stabilizes the short range atomic
ordering, or even creates further amorphization. The crystallinity of the as-deposited Fe–Ni based films
was improved by thermal annealing, and diffraction results indicated that ion beam irradiation on
annealed samples results in grain fragmentation. On bombarding annealed films, the surface roughness
of the films decreased initially, then, at higher fluences it increased. The observed change in surface morphology
of the irradiated films is attributed to the interplay between ion induced sputtering, volume diffusion
and surface diffusion |
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