Annealing Kinetics of Vacancy Defects in Quenched Gold at Elevated Temperatures

A new technique was developed for studying the annealing of supersaturated vacancy defects under comparatively simple conditions at elevated temperatures in gold. A resistance-heated wire specimen mounted in a helium-filled cryostat was (i) gas-quenched from 700°C to an elevated annealing temperature (180°C<̄Ta<̄670°C) where it was held steady for periods between 100 msec and 10 min; and (ii) quenched to 78°K. The total loss of defects was then obtained from electrical-resistivity measurements at 4.2°K. The temperature-time history was obtained using a rapid-data-acquisition system. The annealing data were consistent with a monovacancy-divacancy annealing model in which the divacancy possessed a migration energy of Em=0.69 eV and a binding energy of 0.40 eV. In addition, the model parameters were consistent with available equilibrium vacancy-defect-concentration data and high-temperature self-diffusion data. The results also agreed with earlier work at lower temperatures by Ytterhus and Balluffi and others in which a defect (evidently the above divacancy) dominated the annealing with Em=0.71±0.03 eV. The annealing kinetics were consistent with simple annealing to existing dislocations. Information about the dislocation sink efficiency was also obtained. For Ta<̄483°C the dislocations appeared to act as perfect line sinks present at densities between 0.65 and 5.1×107 cm-2 in the various specimens. Above Ta 600°C the sink efficiency apparently decreased because of a decreased driving force for climb.