DIFFUSION OF IRON AND NICKEL IN SINGLE-CRYSTALLINE COPPER

The diffusion of Fe and Ni in single-crystalline copper was investigat ed in the temperature range from 651 to 870 K and from 613 to 949 K, r espectively. Ion-beam sputtering in combination with secondary-ion mas s spectrometry was employed to measure concentration depth profiles. T he temperature dependence of the diffusion coefficients of Fe and Ni i n copper can be described by D-Fe=(0.10+/-0.03)x10(-4) exp(-2.04+/-0.0 2 eV/kT) m(2) s(-1) and D-Ni=(0.62(-0.21)(+0.31))x10(-4) exp(-2.32+/-0 .025 eV/kT) m(2) s(-1). 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 hig h temperatures. The temperature functions of D-Fe and D-Ni can be desc ribed with the aid of the modified electrostatic model of impurity dif fusion, assuming effective values for the charge difference between ho st atom and impurity.