Ion beam etching is the best way for your problem

Dear Barun

You can use marble reagent for Inconel 718 superalloy microstructure

I used this one and got good results

Marble's Reagent

CuSO4 - 10grams

Hydrochloric acid-50ml Water-50ml

http://www.metallographic.com/Etchants/Etchants.htm

Dear Barun Bharadwaj Dash

Try electrochemical polishing: 125 Сг03 +860 ml Н3Р04. U 36-40 v, time of 10-15 minutes

It all depends on what you are trying to reveal.

For strengthening precipitates and other phases;

Electro-etching in 170 ml of H3PO4 +10mLH2SO4 + 15 g CrO3 at 5 V for 20 seconds will do that.

To reveal grain-boundaries;

1. Kalling's 2 should work if you electro-etch slightly. Alternatively,

2. Swab using a modified Kalling's:- 40ml distilled water + 480 ml HCl +48g CuCl2.

Good luck!

Dear Dr.Barun Bharadwaj Dash

you can see pdf

Try Electrolytic Etching (10% oxalic acid; 6V DC supply). You need to play with the time here. We got very good results around 20 seconds.

Theoretically for grain boundaries, you can use Kalling's reagent No.2 but it didn't reveal anything for me after immersion for about a minute. You can try mixed acid: 15 cc HCl, 10 cc HNO3, 10 cc Accetic acid and 2-3 drops glycerol

You can either try etch the finished parts by 10mL HNO3, 10mL CH3COOH, and 15mL HCl by swabbing on your part.

Or you might want to electroetch the parts by saturated Oxalic acid, or aqua regia under 3-5 volts for 5 seconds.

It worked for me.

Dear Barun Bharadwaj Dash,

The classic reagent for etching superalloys is the Marble reagent.

I also use Hamed Mirzadeh reagent