Metastable alloy formation in lead implanted nickel

Metastable lead-nickel alloys were produced by room temperature random impl antations of 240 keV Pbi ions into Ni(1 1 0) single crystals to a fluence o f 10(16) cm(-2). Rutherford backscattering (RBS)/channeling analysis supple mented with transmission electron microscopy (TEM) showed that the alloy wa s in form of a supersaturated substitutional solid solution with a peak Pb concentration of 2.4 at.% while a fairly small fraction of the implanted Pb was confined within nanoscale precipitates. The precipitates were found to be mostly single crystalline with size in a range from about 2 to 15 nm al though bi-, tri- and even tetracrystals were occasionally observed. Post-im plantation annealing at different temperatures upto 860 K leads to a strong outdiffusion of a substantial fraction of the implanted lead. Upon anneali ng, the lattice occupancy of the originally substitutional lead atoms was f ound to change to different types of lattice locations (regular and displac ed substitutional, octahedral interstitial and random) which appeared to be strongly correlated with the temperature of annealing. (C) 2000 Elsevier S cience B.V. All rights reserved.