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 ($180°\mathrm{C}\overline{<}{T}_a\overline{<}670°\mathrm{C}$) 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 $E^m=0.69\mathrm{}$ 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 $E^m=0.71\mathrm{}\pm 0.03$ eV. The annealing kinetics were consistent with simple annealing to existing dislocations. Information about the dislocation sink efficiency was also obtained. For $T_a\overline{<}483°$C the dislocations appeared to act as perfect line sinks present at densities between 0.65 and 5.1×${10}^7$ ${\mathrm{cm}}^{-2\mathrm{}}$ in the various specimens. Above $T_a\simeq 600°$C the sink efficiency apparently decreased because of a decreased driving force for climb.