Chemical composition of EDS-SEM and Emission Spectrometer is so different

[Best99]

Dear Sirs,

I have got the result from EDS-SEM comparing with Emission Spectrometer of S45C and A2618 samples.

Result was so different. Spectrometer result was OK.

I know that EDS-SEM is only qualitative analysis but when refer from detection range of EDS-SEM it should be no problem.

Could you please advise me about this point. What kind of EDS-SEM can be used correctly for chemical composition analysis?

Thank you.

 

[EdStainless]

Any system on an SEM takes radiation and then uses theory to calculate the chemistry.
These are notorious for having significant errors. After all this is just a secondary function, the SEM is built for imaging.
An OE or XRF unit uses calibration curves built from dozens of reference standards to determine chemistries, this is their primary purpose.

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P.E. Metallurgy, Plymouth Tube

 

[arunmrao]

EDS-SEM analysis is normally done to understand fracture surfaces for any debris or understand segregation effect at the surface. Thus the results of EDS is always combined with SEM studies.

OES results are more accurate and reliable compared to EDS-SEM chemical reports, which can be notorious .

"Even,if you are a minority of one, truth is the truth."

Mahatma Gandhi.

 

[mrfailure]

EDS analysis is semi-quantitative and is usually standardless and not based on calibration. Many limitations in EDS (I recently gave a talk discussing them) so I won't bore you, but it cannot be used for comparison to quantitative spec limits. Results are misleading even on the best of samples (i.e. a polished mount), especially if you make the mistake of using the carbon result that is given. OES is quantitative and uses calibration curves so it can be used to the level that determines conformance.