Secondary grain boundary dislocation structures in gold and silver 〈001〉 twist boundaries revisited

Abstract

A search was made for the presence of localized secondary grain-boundary dislocations (SGBDs) in selected [001] twist boundaries in gold and silver using transmission electron microscopy Screw SGBD networks were detected in near-Σ5, -Σ13, -Σ17, -Σ25 and -Σ29 boundaries in gold and in near-Σ-5 boundaries in silver. The Σ25 and Σ29 networks were observed for the first time and extend the range of SGBD structures observed in [001] twist boundaries in gold beyond that found in earlier work. The observation of Σ5 SGBDs in silver contradicts an earlier claim that these SGBDs are delocalized in this metal. Extensive tests were carried out to verify that all of the observed SGBD images were indeed due to localized dislocations and were not moiré fringe patterns.