Lattice and Grain Boundary Self-Diffusion in Nickel

Abstract

Lattice and grain boundary self‐diffusion coefficients of radioactive nickel 63 into high purity nickel have been measured over the temperature range 650°–475°C. The lattice diffusion coefficients, measured by radioactive counting of the surface, are given by $$D_L\text{=1.9\hspace{0.17em}}\exp \text{(−66\hspace{0.17em}800/RT)\hspace{0.17em}}{\mathrm{cm}}^2{\sec }^{\text{−1}}$$ in agreement with previous measurements at higher temperatures. The grain boundary diffusion coefficients, determined from activity‐penetration data, are similarly given by $$D_B\text{=0.07\hspace{0.17em}}\exp \text{(−27\hspace{0.17em}400/RT)\hspace{0.17em}}{\mathrm{cm}}^2{\sec }^{\text{−1}}$$ and found to be independent of grain diameter in the range of about 0.03 to 0.07 mm.