Shanmugarajan,

there is, as you certainly can imagine, more than one substance able to achieve your target.

And I suppose there will be listed many of them by the metallographic experts on the forum, but the subsequent are the ones which I know.

For the visualization of the materials-macrostructure:

«TUCKER etchant»:

·  15 cm^3: HF (Hydrofluoric Acid)
·  45 cm^3: HCl (Hydrochloric Acid)
·  15 cm^3: HNO3 (Nitric Acid)
·  25 cm^3: H2O (Water)

«FLICK etchant»:

·  10 cm^3: HF
·  15 cm^3: HCl
·  90 cm^3: H2O

«KELLER etchant»:

·  10 cm^3: HF
·  15 cm^3: HCl
·  25 cm^3: HNO3
·  50 cm^3: H2O

For visualizing of the materials-microstructure:

«Hydrofluoric Acid (HF)»:

·  0.5 cm^3 HF (40%) + 100 cm^3 H2O

«Sodium Hydroxide (NaOH)»:

·  1 g NaOH + 100 cm^3 H2O

«VILLELA etchant»

·  20 cm^3: HF (40%)
·  10 cm^3: HNO3
·  30 cm^3: Glycerine

«DIX - KELLER etchant» (for grain boundary etching on AlMgCu-alloys)

·  10 cm^3: HF
·  15 cm^3: HCl
·  25 cm^3: HNO3
·  950cm^3: H2O

«Phosphoric Acid» (For visualizing Al3Mg2 in AlMg-alloys. Etching time = 30 min.)

·  9 g: H3PO4 (cryst.)
·  100 cm^3: H2O

«SCHULZ - WASSERMANN etchant» (For AlZnMg-alloys)

·  3 cm^3: HF (40%)
·  12 cm^3: HCl
·  120 cm^3: HNO3
·  300 cm^3: Bichromate-solution (10%)
·  500 cm^3: H2O

I guess in the very most cases you will achieve good results by using pure and fresh "Sodium Hydroxide (NaOH)" or "Hydrofluoric Acid (HF)", but perhaps have others different views.

Please take care when operating with these etchants in general, but in particular with the latter!

Best regards,
Stephan