I am trying to capture the XRD intensity peaks for a part made up of nickel alloy. When I try to capture the peaks, I am unable to get them. Can someone help me out why is this phenomenon happening and what are the reasons behind it? If any literature available with relevant to the non availability of intensity peaks in XRD, please do help me out.
Thanks in advance
Hemnath
#XRD #MetalADDITIVEMANUFACTURING #Residualstress
Dear Hemnath A K ,
Your description is superficial; more details are necessary.
Are you trying to get the X-ray diffraction over a surface with elevated rugosity?
Are you sure the X-ray beam is scanning the desired surface area?
I understood the experiment is "in situ," which may not represent the minimum necessary diffraction condition for a reliable experiment.
Your nickel alloy may have texture, and you are probing an inappropriate angular range.
Some alloys are specifically designed to have an amorphous characteristic; it fulfills industrial needs, be sure it is not the case, usually obtained by quenching.
Sometimes, to prepare the sample, even metallic ones, a reliable X-ray setup measurement is usually necessary, by milling the alloy, ball orbital milling that may or may not be ideal condition.
Besides, there is the possibility to modify the measurement conditions with a higher voltage or current to have a better signal; the operator knows how much it is safe to use. You are increasing the power of the beam.
X-ray in alloys is well described in the literature. Expend some time searching some specific papers based on the history of your sample.
Best regards
WNM
Hello Hemnath... have you obtained the relevant peak in powder (powder used in experiment) XRD data?
you can try with lower step size...look for oxides/carbides/intermetallic peak position.
Dear Hemnath A K ,
Your description is superficial; more details are necessary.
Are you trying to get the X-ray diffraction over a surface with elevated rugosity?
Are you sure the X-ray beam is scanning the desired surface area?
I understood the experiment is "in situ," which may not represent the minimum necessary diffraction condition for a reliable experiment.
Your nickel alloy may have texture, and you are probing an inappropriate angular range.
Some alloys are specifically designed to have an amorphous characteristic; it fulfills industrial needs, be sure it is not the case, usually obtained by quenching.
Sometimes, to prepare the sample, even metallic ones, a reliable X-ray setup measurement is usually necessary, by milling the alloy, ball orbital milling that may or may not be ideal condition.
Besides, there is the possibility to modify the measurement conditions with a higher voltage or current to have a better signal; the operator knows how much it is safe to use. You are increasing the power of the beam.
X-ray in alloys is well described in the literature. Expend some time searching some specific papers based on the history of your sample.
Best regards
WNM
First of all, What is the exact composition of Ni-alloy. What is the at. percentage of Ni?
Dear Sunil Yadav I have obtained the desired peak for 5 samples made out of the same IN625 powder with different process settings. Just 2 of the samples are not showing any peak values. As per your suggestion I will check it out brother.
Dear Wagner Da Nova Mussel sir. Thank you so much for your detailed explanation about my question. The experiment is not "in-situ" and the XRD study was performed on a previously fabricated INCONEL625 sample. As u have asked, the surface is somewhat rugose and i am sure that i am scanning the desired surface area. In addition to that as you suggested, the XRD study was tried with various operating conditions but same results.
If texture is present, what might be the effect? Could you please help me out?
Thanks in advance
Hemnath.
Dear Hemnath,
from what I understand, you are trying to determine the RS on the surface of your IN625 specimens. Check your d_spacing vs. tilt angle and intensity plots, that might give you an idea about texture effects (i.e. wavy distribution). No peak at all could be a grain size effect, which is unlikely but could happen.
Maybe you can expand a little more on your experimental set-up?
Best regards
Maximilian
Dear Hemnath A K ,
answering the second question, if the surface intense texture is present, the beam scattering would be severe. Therefore, the peak intensity would decrease drastically or even will not be present.
I suppose a surface polishing could be done to check the resulting material; even it is not of your interest to alter the surface characteristics.
I can also suggest the use of raising angle experiment as a complimentary experiment, it will probe the surface, as far as your incident angle is lower as 0.5 degree or so.
Best regards
WNM
Dear Maximilian Sprengel ,
Thanks much for your response sir.
Yes exactly what you said is true that am trying to measure residual stress on the top surface of IN625. If its a grain size effect, there might also be no peak occurrence? Can you suggest me some supporting research article sir, where they faced a similar issue?
Thanks in advance
Hemnath
Dear Wagner Da Nova Mussel sir,
Thank you for your suggestion. As I am interested in measuring the residual stress on the surface, suppose if I do surface polishing, won't it relieve the stresses on the surface?
Thanks in advance
Hemnath
Dear Hemnath,
the NPL has a very good practice guide: Determination of Residual Stresses by X-ray Diffraction – Issue 2 GPG52 - NPL
If you want to go further down the route of the determination of RS using x-rays, try to look for books from Macherau and Hauk.
Best regards
Dear Hemnath A K ,
Yes, you will release the surface tension after polishing if the residual tension is only superficial. If the observed tension is already surface propagated, it still present, even after polishing.
I suggested polishing the surface to probe the composition of the final material, as some loss of stoichiometry, stacking fault, preferred orientation on crystallising intentionally obtained by some external magnetic field and some other effects that may result in a sort of directional stress. It would be another information over the whole sample. Even trapping impurities may result in some stress in the sample. Perhaps polishing, some trapping material may be evidenced.
That would be a complementary experiment to collect some extra information.
Best regards
WNM
Dear Maximilian Sprengel sir,
Thank you so much for the guidance and suggestion on the study materials to be referred. It will be really useful for me.
Hemnath
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