Thanks EdStainless. Yes I have. This is a rotating air seal and I am doing in-situ. I have also tried numerous electrolitic etchants. The grain size should be 10 or finer. I have beautiful pricipitates and a very even microstructure, but need to measure grain size.
I agree with metengr that if one of the stronger etchants from the list doesn't work, then contact George Vander Voort directly. FYI, George is no longer with Buehler. He set up his own consultancy, and is working with Struers and other companies. The website above has his contact information.
Thank you, all. I am trying to determine if the component saw an excessive temperature condition. I still see coarse and fine gamma prime; therfore I agree with EdStainless that the Rene'95 is still in the correct heat treat condition.
The employees at ATI are former Crucible Research scientists, and they very likely have experience etching Rene 95 samples for the former Crucible Compaction division. Ask for Andre. If he doesn't know what etchant to use, he can probably direct you to someone who does.