Swift heavy ion induced surface and microstructural evolution in metallic glass thin films

Abstract

a b s t r a c tSwift 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 Au 9+ beam with fluences ranging from 3 Â 10 11 to 3 Â 10 13 ions/cm 2 . 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.

Resistance to He2+ irradiation damage in metallic glass Ta38Ni62

“…Surface morphology evolution of the ion beamirradiated solid material was caused by competition between ion bombardment-inducing roughness and internal material transportation-inducing smoothness [33]. The metallic glass surface was smooth because of its disordered structure, without the orientation-dependent sputtering phenomenon in crystal materials [34].…”

Effect of heavy ions irradiation on the properties of benzil crystals

“…The increased roughness at high fluence irradiation can be explained by the collision cascade as a result of Ni ion‐benzil interactions. The energy received by the displaced atoms is higher than the binding energy and the atoms leave the surface overcoming the energy barrier …”

Structural, topographical and magnetic evolution of RF-sputtered Fe-Ni alloy based thin films with thermal annealing

“…ξ for pristine film, and for films annealed at 400°C and 600°C are 1.6, 1.8 and 2.1, respectively. Herring and Mullins have reported the possible surface mechanism as plastic flow driven by surface tension, evaporation condensation, volume diffusion and surface diffusion for ξ values 1, 2, 3 and 4 [21,28,29]. The ξ values increases on annealing.…”

“…Senoy et al and Hysen et al reported the fabrication of thin films from composite targets using vacuum evaporation [19,20]. They also studied annealing and swift heavy ion irradiation effects on these films and reported the formation of Fe-Ni nanocrystals with annealing [21,22]. These nanocrystalline structures precipitate after annealing at 400°C.…”