Precipitate assemblies formed on dislocation loops in aluminium-silver alloys

TL;DR

This study investigates the formation and structure of precipitate assemblies on dislocation loops in aluminium-silver alloys, revealing new assembly morphologies and the role of stacking faults in their nucleation and growth.

Contribution

It uncovers previously unreported precipitate assemblies on dislocation loops and elucidates the influence of stacking faults on their formation and development.

Findings

Precipitate assemblies consist of 5-7 precipitates on dislocation loops.

Assemblies adopt a tetrahedral bipyramidal shape.

Stacking faults control nucleation and growth of precipitates.

Abstract

A detailed study of the precipitation of the \gamma' (AlAg2) phase in undeformed aluminium-silver alloys has been conducted. Several previously unreported features were observed, including the formation of discrete three-dimensional assemblies comprised of 5-7 precipitates on faulted dislocation loops. The precipitates assemblies adopted a morphology approximating a tetrahedral bipyramidal assembly. The bounding defect of the stacking fault was found to control both the nucleation of additional precipitates which was responsible for the formation of the assembly structure and also the growth characteristics of individual precipitates with these assemblies.