Hi guys, I am doing a research about the welding under nitrogen atmosphere. I made an alloy and welded it using arc under nitrogen atmosphere. In order to quantify how much nitrogen was dissolved into weld area, I first cross-sectioned the weld area, polished and used XPS depth profiling at first due to its high sensitivity. I used multipek to do analysis and found that result was not convincing since it showed a very weird metal elemental compositions. After reading some literature and consulting technicians, it seems that XPS is suitable for qualitative analysis (relative amount) but not quantification. But for a rough guess there would be around 1% of nitrogen dissolved from XRD measurement.
Then I turned to WDX after reading some nitrogen steel literature published in 60s-80s. After consulting technicians, they said WDX was not accurate to measure nitrogen content too. It makes me confused since most of the papers studying nitrogen in alloy used WDX and WDX is designed to measure low Z elements with better detection limit.
Is it impossible to use WDX to measure nitrogen (around 1at %)? If not then how does the structural steel manufacturer give you production cert with nitrogen content as low as 0.2%? ToF-SIMS is not suitable for us since our financial fund is not enough and it is not worth it.
Dear Kamsing,
I guess the amount of nitrogen will be very small - smaller than 0.1 wt.%. There are techniques that are better for you task than WDX, for example Glow Discharge Spectrometry. This is what I suggest.
EDIT: Also the manufacturer uses this technique, there are several types for measuring C, N, S, O and there are different types for measurement of interstitial and substitutional elements at once.
I agree that 1% is too high value for nitrogen solution in metals. May be you have nitrates as a separate phase, may be something was wrong with your analysis.
Anyway, nitrates or 1% solution are pretty good candidates for WDS semiquantitative analysis if your aim is to study distribution of nitrogen on a micro scale. If you want just a bulk analysis, there are better methods.
Thanks for answering, Mr. Dusevich and Mr. Wang. Technician also said the same thing that standard is needed. The problem is that the composition of my sample is custom made. Where can I buy such sample?
https://www.2spi.com/category/metals-minerals-standards/
https://www.tedpella.com/calibration_html/UHV-EL_Reference_Standards_for_EDS_WDS.htm
Etc.
Mr. Wang and Mr. Dusevich, thanks for answering, Dr. Wang, I made my sample by welding but I can borrow arc melter from other group to make a alloy standard. I think making a standard by using nitride powder would be better due to time saving and cheaper. Thanks for answering.
You cannot prepare alloy standard by yourself. Do not even try.
You can use stoichiometric compounds (like NaCl) as standards (if they are sufficiently pure).
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