Méthode expérimentale d'etude du germe de boucle de dislocation : détermination de sa taille

Abstract

An experimental method for determining the dislocation loop nucleus size

The principles of an experimental method for determining the dislocation loop nucleus size are described.

The basic experiment for this method consists in measuring the dimensional changes of a single crystal irradiated under an uni-axial stress. By favouring some Burgers vectors to the detriment of others, the stress induces some artificial anisotropy which is directly related to the nucleation process. More precisely, the induced-growth coefficient measuring this anisotropy is shown to depend strictly on the vacancy and interstitial nuclei sizes. The statistical hypothesis which leads to this result is discussed.

Finally, it is shown that the extra stresses induced by the grown-up dislocation loops on a nucleating loop have no influence on the measured dimensional changes.