Annealing reactions in lead implanted copper

The terminal solubility of Pb in Cu is extremely low and does not exceed 0.09 at.% at 875 K. Ion implantation of lead ions at 100 keV into Cu single crystals produces metastable solutions. Annealing of the samples causes redistribution of the implanted atoms to equilibrium or near-equilibrium aggregate states which may be reflected in a change in the type of impurity lattice location in the host matrix. We have studied the effect of annealing on single crystalline Cu implanted at temperatures around 375 K with Pb to a concentration of a 1-2 at.%. Rutherford backscattering/channeling analysis and transmission electron microscopy of the as-implanted samples have shown that the implanted Pb forms a supersaturated solid solution with a major fraction of the Pb atoms located on substitutional sites in the host lattice or in very small clusters. At higher annealing temperatures up to 870 K more than half of the lead is lost by outdiffusion and the remaining fraction forms nanometer-sized crystalline inclusions by cooling to room temperature. Melting and solidification temperatures of the inclusions have been followed by in situ channeling measurements