Influence of oxidizing and reducing treatments on vacancy clustering in gold

Abstract

The stacking-fault tetrahedra observed in specimens of gold, quenched from a reducing atmosphere, are found to be smaller by a factor of four than in specimens quenched from an oxidizing atmosphere. This result is discussed in terms of the different distribution of impurities after oxidation and reduction. The effect of the impurities on the measured stacking-fault resistivity is also examined. It has been observed that tetrahedra grow during isothermal annealing at 40°c. The results of experiments where quenched specimens are aged at different temperatures, between 40°c and 200°c, support the hypothesis that the initial tetrahedron nucleus is a small three-dimensional vacancy cluster. These experiments show that the proportion of clustered vacancy defects which are not tetrahedra, but dislocation loops, increases with increasing ageing temperature. In the specimens pre-treated in an oxidizing atmosphere, it was found that the stacking-fault tetrahedra commonly occur in rows along the 〈110〉 direction.