Optimizing the surface of multiphase Al alloys for successful EBSD analysis

Gatan instrument used

PECS™ II and EDAX^® Pegasus system with Octane Elect, Velocity™ Super, and APEX™ software

Background

To obtain valid electron backscatter diffraction (EBSD) orientation measurements, the true structure of a specimen must be undistorted and continuous to the surface. Any surface contamination and damage introduced during specimen preparation needs to be minimized. On soft materials, such as aluminum, it is very difficult to prepare the sample by mechanical polishing without introducing a thin distorted surface layer that obscures the real microstructure. When secondary phases with different polishing responses are present, simultaneously getting a suitable specimen surface for all phases is even more challenging. Broad beam ion milling provides a way to remove the distorted layer from the entire surface without risking additional damage by mechanical contact.