I recommend you the following etching solution

H2O 10 ml

C2H6O (Ethanol) 100 ml

C2H4O2 (Acetic Acid) 5 ml

C6H3N3O7 (Picric Acid) 5g

I used to reveal the grain structure of pure magnesium and magnesium alloys

Hello! You need AC-2 Electrolyte (Struers)

Distilled water 10-15ml

Ethanol 100 ml

Acetic acid 5ml

Picric acid( yellow colour poisonous substance handle with care ) 5 gm;

But dipped AZ91 for 10- 30 sec in this solution......start with 10 sec if microstructure appears then good if not appears then go for 15 sec and so on till microstructure appears....

Dear Sarvesh Swamy,

A recommended composition of etchant solution for AZ91D alloy is:

Ethanol - 60 %

Distilled water - 35 %

Glycerin - 20 %

Lactic acid - 10 %

Phosphoric acid - 5 %

Citric acid - 2 %

Try with 6-12 Volts for 2-4 seconds.

Thank you.

For those who are going to use Picric acid; be careful with this. Picric acid can become explosive under certain conditions.

I hope this link would help you:

https://www.metallographic.com/Metallographic-Etchants/Metallography-Etchants.htm

According to the following references, acetic glycol solution (20 mL acetic acid, 1 mL HNO3, 60 mL ethylene glycol, and 20 mL water) could be used for metallographic investigations of AZ91 magnesium alloy.

[1] Article Effect of Rare Earth Elements on High Cycle Fatigue Behavior...

[2] ASM Handbook, Properties and Selection: Nonferrous and Special-Purpose Materials, vol.2, ASM International, USA, 1992.

I think this paper may helpful for you.

http://library.nmlindia.org/FullText/MC54054315.pdf

All the best!

Dear researcher;

You can use the following reference:

Article Effect of Rare Earth Elements on High Cycle Fatigue Behavior...