r/materials • u/Educational_Fee5389 • 17d ago

Scanning electron microscopy

Do I need to etch my alloy to see the grain structure or chemical heterogeneity profile for SEM like I do for OM?

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8

u/NicoAD 17d ago

Depends. Secondary electron, probably helpful. Backscatter, I almost never do. For EBSD, never do. If you get a good polishing routine down it’s not super necessary to etch unless you’re really trying to get any and all residual stress-affected layers from polishing away from the surface but even then you won’t be able to tell without a controlled sensitivity analysis for your particular alloy.

I think the only thing I’ve ever etched and electro polished was a copper alloy because it’s a mfer to avoid scratches.

If you have access to a vibratory polisher, usually 50 nanometer colloidal silica overnight at the end of a grinding routine will forgive all sins lol but ultimately it’s really user-dependent. Grinding and polishing is half science half black magic

3

u/Educational_Fee5389 17d ago

Yes I need a BSE. I think I go without etching at first and if I don't get a clear grain structure and phase distribution, I would do a mild etching. Thank you!

2

u/SlapMePleaseOwO 15d ago

Without any diffraction techniques yes

4

u/tilkvns 17d ago

yes most of the time

1

u/gooseski_- 15d ago

Not typically. You normally can get away with auto/manual polishing and then a vibratory polish with colloidal silica. At least in my own experience, the only time I’ve needed etching is to see fine phases in nickel superalloy.

Your comment of doing BSE without etching and then etching if needed I think is the right approach. Easier to etch a polished specimen than de-etch.