I'd like to do some texture analysis via electron backscattered diffraction (EBSD) on high-purity chromium. First attempt with colloidal silica (mix with hydrogen peroxide). Able to see grain structures under optical microscope, but no Kikuchi patterns appeared when brought under the SEM. Is it possible that the colloidal only etched the grain boundaries, but not the grains? Many thanks for your answers.
Bo
I have to admit that I did not measure pure chromium yet but I would assume if you see the grains you either need to polish a bit longer, or you have some reaction on the surface which prevent any visibility of patterns formed in the grains below the generated layer on the surface. Alternatively you can use ion etching in order to prevent water access.
I can see the grains, just not the patterns. It is very likely that reactions occur on the Cr surface that limits the visibility of patterns. Will try ion-etching as well! Thanks for the suggestions!
Bo
Usually chemical etching is the preferred procedure since you do not cause deformation on the sample surface. If your Cr should water sensitive (sounds very strange to me but a) I am no chemist and b) never investigated Cr by myself) you need to prevent the polishing steps using water or the cleaning with water after chemical etching. Only ethanol should be OK. Also ion etching has the potential to implement defects directly on the surface so that you might get more blurred patterns that you expect. But this you have to test in order to get a feeling how your material reacts. The best way is to find two or three different ways and compare the results. Finally you should use the artifact-free (or minimal) version. For some phases it is even easier to generate first an oxide layer (e.g. by color etching) and remove this chemically in a second step.
Hello,
we are currently doing EBSD on electropolished high-purity chromium: works fine, beautiful patterns...
How long did you polished ? in both case: 1) using diamond suspension before final polishing 2) using colloidal silica mixture solution (final polishing).
If damaged-layer is still remained thorugh specimen thickness, pattern appeared with blurred lines.
In my case, when I prepared alloy sample with delicate surfaces (e.g. Ti alloy, TWIP steel, nitrided steel), I usaually polished them at least 20 min for diamond suspension step and 30 min for colloidal mixture step.
For your convinience, I use collodal silica mixed with ethanol (1:1 ~ 1:3).
Please refer the attached articles (Dr. Joo-Hee Kang`s paper), although it was written with Korean, you can figure out the sample preparation method through Table.
Best.
Many thanks both Claire and Jeongho. Will allow longer polishing time and see how it goes. May I ask what is the etchant you were using for high-purity Cr? Thanks again.
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