Pressure Effect on Defect Migration in Aluminum

The effect of hydrostatic pressure up to 9.5 kbar on the annealing rate of the excess resistivity in quenched aluminum was measured in two annealing regions. One was at —65°C following quenches from 580°C and the other at 0°C following quenches from 331°C. Effective activation volumes for motion were determined to be (3.0±0.3)×${10}^{-24\mathrm{}}$ ${\mathrm{cm}}^3$ and (2.8±0.3)×${10}^{-24\mathrm{}}$ ${\mathrm{cm}}^3$, respectively. These results were interpreted in terms of vacancy and divacancy motion. The -65°C anneal value represents the motion of divacancies. The 0°C anneal value cannot unambiguously be assigned to a single type of defect. However, assignment of a single-vacancy motional volume close to the 0°C anneal value is consistent with these and diffusion results if it is assumed that there is a divacancy contribution to self-diffusion in aluminum, or that the motional volume is temperature-dependent.