Lattice and grain-boundary diffusion of phosphorus in commercially-pure copper

The diffusion rates of phosphorus in 3 batches of commercially-pure copper with different impurity content have been determined in the temperature range 574 to 1046° using the tracer-sectioning technique. There is clear evidence of grain-boundary diffusion occurring below 720°. The three activation energies and preexponential factors obtained for volume diffusion areQ _l = 1.43 eV, 1.44 eV, 1.43 eV;Dqi = 7.02 × 10^-3 cmVs, 7.98 x 10^-3 cm²/s, 4.38 × 10^-3 cm²/s. For grain-boundary diffusion the respective average values are Q_b = 0.70 eV and D_obδ≈ 4.2× 10^-7 cm3/s.