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J. Österreicher, M. Kumar, A. Schiffl, S. Schwarz, D. Hillebrand, G. Bourret:
"Sample preparation methods for scanning electron microscopy of homogenized Al-Mg-Si billets: A comparative study";
Materials Characterization, 122 (2016), 63 - 69.

Characterization of Mg-Si precipitates is crucial for optimizing the homogenization heat treatment of Al-Mg-Si
alloys. Although sample preparation is key for high quality scanning electronmicroscopy imaging,most common
methods lead to dealloying ofMg-Si precipitates. In this articlewe systematically evaluate different sample preparationmethods:
mechanical polishing, etching with various reagents, and electropolishing using different electrolytes.
We demonstrate that the use of a nitric acid and methanol electrolyte for electropolishing a
homogenized Al-Mg-Si alloy prevents the dissolution of Mg-Si precipitates, resulting in micrographs of higher
quality. This preparationmethod is investigated in depth and the obtained scanning electron microscopy images
are comparedwith transmission electronmicrographs: the shape and size ofMg-Si precipitates appear very similar
in either method. The scanning electron micrographs allow proper identification and measurement of the
Mg-Si phases including needles with lengths of roughly 200 nm. These needles are β″ precipitates as confirmed
by high resolution transmission electron microscopy

http://dx.doi.org/10.1016/j.matchar.2016.10.020