In situ study of radiation damage in thin foils of gold by high voltage electron microscopy

Abstract

Thin foils of gold have been irradiated at room temperature using 2·5 MeV electrons in a high voltage electron microscope. By examination of defect clusters for several orientations and impurity contents (1 to 100 at. p.p.m.) it is possible to define four irradiation stages. During the first stage, interstitial dislocation loops grow with a t ^1/3 time dependence only in thicker areas (< 1200 Å). Stacking fault tetrahedra appear during stage 2 and exhibit ordering during stage 3; they collapse into vacancy loops during stage 4. During these latter stages, the time dependence for interstitial loops growth is no longer t ^1/3.

A kinetic model for defect concentrations has been developed, taking into account both surface diffusion and impurity concentration. Experimental and computed results both agree with regard to interstitial loop densities and sizes as a function of time, thickness and purity.

The ordering processes of stacking fault tetrahedra are found to be consistent with models based on elastic interactions between defects.