Observation of in-plane oriented Guinier-Preston zones in Al-Cu

Known for a long time, the first metastable precipitate which forms in Al-Cu alloys during natural ageing are the so-called Guinier-Preston zones (GPZ), platelets of Cu on {100} planes of only one atomic layer thickness. Only with the development of aberration corrected transmission electron microscopes (TEM), direct observation and imaging of these platelets was possible, but with the restriction, that only edge view was possible. Here we show that under appropriate conditions an observation in a plan-view is possible and allows further insight into the shape and arrangement of the GP-zones. Furthermore, this demonstrates that single atom detection of one Cu atom in a column of Al atoms is possible.

Automated summary

It has been known for a long time that the first metastable precipitates in Al-Cu alloys, called Guinier-Preston zones (GPZ), are platelets of Cu on {100} planes with a thickness of only one atomic layer. Until now, the direct observation and imaging of these platelets have only been possible in edge views using aberration corrected transmission electron microscopes (TEM). However, our study shows that under suitable conditions, plan-view observations are possible, providing further insight into the shape and arrangement of the GP zones. Furthermore, we have demonstrated the ability to detect single Cu atoms within a column of Al atoms.