Point defects in gold

Thin foils of pure gold (99,999%) were quenched into water from 700 to 1000 °C. Also foils of various purities (impurity concentrations up to 0.2 atomic percent Cu) are cold‐rolled at temperatures below −40 °C, and the recovery of the electrical resistivity studied between −40 °C and + 300 °C. Fast quenches from 700 °C and 1000 °C resulted in the freezing‐in of single vacancies. The energy of migration was found to be 0.83 ± 0.02 ev. After slow quenches from 800 to 1000 °C double vacancies appear to be the predominant defects, with an energy of migration of ≦ 0.60 ev. The cold‐rolled specimens exhibit pronounced stage III recovery with an activation energy of 0.71 ± 0.02 ev and second order kinetics. Stage IV recovery is not pronounced. The recovery in stage V is dependent on the impurity concentration and the degree of deformation. An interpretation is given of the recovery spectrum of gold based on results obtained on gold only (not on analogies with other metals). With rising temperature the recovery processes are the annihilation of close pairs (stage I), then of interstitials and vacancies with smaller interaction (stage II), and finally the migration of free interstitials (stage III) and free vacancies (stage IV). Other processes may be superposed depending upon the treatment. Some quantitative evaluations of the kinetics are given in the appendix. It is found that, after quenching, homogeneous nucleation of a large density of small vacancy clusters may take place.