Phase transition and diffusion of Ni atoms in aluminum during implantation

Abstract

Ni ions are implanted into aluminum with high ion flux range from 9 to 45 μA/cm 2 and dose range from 1×10 17 to 1×10 18/cm 2 at elevated temperatures of 200°C and 400°C, respectively. X-ray diffraction (XRD) spectra show that NiAl 3, NiAl, Ni 2Al 3 and Ni 2Al 18O 29 phases are formed. Rutherford backscattering spectroscopy (RBS) indicates that a profile of Ni appears in Al around the depth of 230 nm and with the atomic concentration of ∼11%, when Ni is implanted to a dose of 3×10 17/cm 2 with ion flux of 45 μA/cm 2 (400°C). If the dose increases to 1×10 18/cm 2 at the same ion flux, the penetration of Ni ions in Al can reach a depth of 1100 nm, which is 21.5 times greater than the ion projected range R p (48.8 nm). The results show that long-range diffusion takes place due to the intense atom collision cascades during the ion implantation with high ion flux. The diffusion coefficient increases greatly with the increase of the ion flux and dose. The Ni diffusion coefficients and retained dose in Al are calculated. The results show that the Ni retained dose and Ni diffusion coefficient in Al increases obviously during implantation with the high ion flux and high ion dose. When C atoms are also implanted Ni atom motion is facilitated. The phase transition process was observed, when the ion dose increased from 10 17 to 10 18/cm 2; the diffraction peak intensity of NiAl 3 showed a marked increase obviously, but the change of diffraction peak intensity for the Ni 2Al 3 phase was minimal.