The implantation of 240keV Pb+ ions into a Ni (110) single crystal at room temperature or 470K, to a fluence of 1016/cm2, resulted in the formation of a metastable supersaturated solid solution having a maximum Pb concentration of 2.4at%. Rutherford back-scattering/channeling analysis and transmission electron microscopy showed that, in the as-implanted state, most of the Pb atoms were distributed on substitutional lattice sites in the host matrix while a small fraction of Pb was confined within nanoscale precipitates. Most of the precipitates (2 to 15nm) were monocrystalline, although bi-, tri- and tetra-crystals were sometimes observed. Upon heating, decomposition of the metastable alloy occurred, with a strong out-diffusion of a large fraction of Pb to the surface. By means of angular scan channeling analysis, the lattice locations of the implanted Pb atoms were monitored directly during in situ isochronal annealing at up to 860K. Thermally activated formation of Pb-vacancy complexes was found to cause originally substitutional Pb atoms to adopt other lattice-site locations. The normal and distorted substitutional, octahedral interstitial and random locations of the Pb atoms appeared to be strongly related to the annealing temperature.

Solute-Defect Interactions in a Metastable Pb–Ni Alloy Formed by High-Fluence Ion Implantation. V.Touboltsev, J.Räisänen, M.Kolodyazhnaya, E.Johnson, A.Johansen, L.Sarholt: Journal of Applied Physics, 2002, 92[2], 895-901