Diffusion of iron and nickel in single-crystalline copper

The diffusion of Fe and Ni in single-crystalline copper was investigated in the temperature range from 651 to 870 K and from 613 to 949 K, respectively. Ion-beam sputtering in combination with secondary-ion mass spectrometry was employed to measure concentration depth profiles. The temperature dependence of the diffusion coefficients of Fe and Ni in copper can be described by $D_{\mathrm{Fe}}=(0.10\mathrm{}\pm 0.03)\times {10}^{-4\mathrm{}}\exp (-2.04\mathrm{}\pm 0.02 \mathrm{eV}/kT)$ ${\mathrm{m}}^2$ ${\mathrm{s}}^{-1\mathrm{}}$ and $D_{\mathrm{Ni}}=\left({0.62}_{-0.21\mathrm{}}^{+0.31\mathrm{}}\right)\times {10}^{-4\mathrm{}}\exp (-2.32\mathrm{}\pm 0.025 \mathrm{eV}/kT)$ ${\mathrm{m}}^2$ ${\mathrm{s}}^{-1\mathrm{}}$. These results are compatible with earlier high-temperature tracer data. A combination of those with the present low-temperature data reveals a curvature in the respective Arrhenius plots. This curvature is ascribed to the contribution of divacancies at high temperatures. The temperature functions of $D_{\mathrm{Fe}}$ and $D_{\mathrm{Ni}}$ can be described with the aid of the modified electrostatic model of impurity diffusion, assuming effective values for the charge difference between host atom and impurity.