A. Manhard, G. Matern, M. Balden
June 11, 2013
The different stages of the polishing process of polycrystalline tungsten samples were investigated by scanning electron microscopy of both the sample surface and of cross-sections prepared with the help of a focused ion beam. It is shown that a distortion layer is present at the sample surface after mechanical fine grinding and even after polishing with diamond suspension, although the sample has a mirror-like finish. A sufficiently long chemo-mechanical polishing step using an alkaline colloidal silica suspension was able to remove this distortion layer. Although electropolishing produced an even smoother surface, the microstructure quality after chemo-mechanical polishing is comparable to that of an electropolished sample.