Sometime the contrast of nitrided layer is not much visible, and it also depends upon the steels/alloys nitrided. I suggest to try different etchent.

Dear Akeshwar, can you please suggest me proper etchent. currently i m working on CoCrMo alloy.

I would recommend to use first a Ni plating (several 100µm) in order to "stabilize" your surface (in order to prevent rounding effects). Then you should be able to perform a common cross-section preparation for EBSD, EDS or possibly also etching. (I simply assume that you use scanning electron microscopy (SEM) for imaging).

The N content should become visible by backscattered electron (BSE) contrast already, however, in this case you need a very flat surface (cross section ion polisher). If the contrast is quite strong a simple polishing with 1µm diamond might help as well since it prevents orientation contrast from surface topography. Such data are often more precise since the interaction volume of the visible BSE signal is better than energy-dispersive X-ray spectroscopy (EDX) in SEM.

I think seeing the nitrided layer just after the polishing step will be difficult, if not impossible.

I don't have experience with the alloy you studied so an appropriate enchant cant be suggested. Didn't you find anything in the literature about a similar alloy as yours?

In the case of maraging steel after surface nitriding, the nitrided layer can be revealed by the band slope based image quality EBSD map. Due to the more extensive straining of the nitride to the surrounding bulk iron lattice than the unnitride zone, the band slope reduces of the nitrided layer is lower, thus appearing "darker" in the map, see the reference below:

Article Precipitation in simultaneously nitrided and aged Mo-contain...

@ J. Wu: I agree with you, however, you could try to average the gray scale image along the interface. It is sometime surprising how sensitive this can be. I am not sure what he is doing (EBSD or only imaging or only light microscopy and etching). Therefore I did not went further how nitride layers can be imaged by EBSD. We even do not know how much N he can "pump" into his structure... In meteorides you even find nitrides which you can very easily see by BSE, whereas EBSD might be challenging or is possibly nor very reliable.

I didn't have any experience with your alloy, you can also prepare the surface as advised by Dr. Nolze, i.e by Ni plating. You can also use micro hardness indentation to know the approximate layer thickness till you are unable to see it.

Dear All,

Thanks for your reply.

I tried with polish surface up to 1 um (for 10 min). But could not find any sign of nitrided layer even in the backscattered detector. I have also performed SIMS were we can exactly see a proper depth profile of nitrogen which is around 1 um.

I can try with Ni plating but currently, we don't have the Ni electrolyte. Dear. wu I check literature regarding this but didn't find proper procedure for that.

thanks

Is anyone has Idea about HCL+H2O2 (1:1 ratio)?