I have tried Keller's, HF, Poulton's and modified Poulton's but nothing turned out in favour.
Article A New Metallographic Technique for Revealing Grain Boundarie...
I have had decent luck using Barkers' reagent (4 mL HBF4 in 200 mL DI water. Pre-etch for 20 s, then apply 20 V/dc for ~1.5 min, depending on grain size). I've attached an example of my results. You MUST use polarized light with a color filter to achieve results like the attached image. I also recommend Gunabalan's answer as well.
Thank you all for your suggestions. I am now able to reveal the grains.
You can also try EBSD technique...... much more informative microstructure you can obtain.
To me, the best method for etching is electro-etching by Barker reagent.
Good luck
Dear Vikas Upadhyay
Keller reagent is the best one the only thing that should be in taking care is the swipe or holding time of the sample in the etching solution, as AA6082 is the medium strength alloy so the grains inside the base material is not so proactive to retard the acidic attack of the solution. Try the killer one with varying the holding and dip time, it definitely works.
Good luck
Regards
use Tucker's reagent etchant for aluminum 6082 : 25 ml of water, 15 ml HF, 25 ml HCl, 15 ml HNO3.
immerse or swabs of your specimen for 5 second.
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