Two phases, bcc iron and fcc iron is set for calculation.
I didn't add any background to the pcr file yet.
Scale, b factor, u w v (FWHM), IG are set for refinement.
I couldn't find a parameter for Ka2 and monochromator.
Bruker D8 was used to obtain data.
I guess you only use the wrong lattice parameter for austenite. Try 3.59 and I guess fullprof will also refine the residual austenite correctly. I shortly did it with PowderCell and without the data the simulated diffractogram alreayd does not look that bad.
did you import the 2 phases into your PCR file? because from the pic you can only see one phase. nomally there is a little offset of the theoretical positions. so maybe the import did not work well. I think it is missing completely. FYI: you will find the options for the wavelenght and monochromator in:
patterns > data file/peak shape > refinement/simulation( for Wavelength)
patterns >geometry/IRF >corrections( for monochromator)
best
Thank you Greg and Pascal. I changed the lattice parameter and the peaks didn't change. Also, both phases are inserted correctly in the file. I think I have to find some way to insert instrument values. I am trying!
I did the refinement in MAUD and the calculated peaks are like in the picture. any suggestion for better fit!?
I would say that your peak width description is suboptimal. Reasons can be anisotropic peak broadening, Debye-Waller factor, and if the intensity is then not correct anymore, texture. For austenite the probability to find a good match is very low since you only have the first peak. But for the phase fraction it is very important to describe bcc correctly in order to exctract the residual austenite part. Therefore, try to focus first on bcc to get a more or less ideal description.
Dear Gert, I have done some changes in anisotropic peak broadening, as you suggested but on austenite and also I changed Biso for martensite, the peaks are now fitted better, but still there is problem with the martensite peak at 200. Do you think it is because of texture (preferred orientation) ?
If so how can I get better fit on 200?
Martensite shows typically a tiny tetragonal distortion, i.e. you should perhaps look whether this approach will generate a better match. If you do not kniow how to do it, could you send me the data set as angle-intensity table?
The image is the final refinement which I think has a good match with the experimental pattern. GoF = 1.6205
In the last refinement as suggested by Gert, I refined anisotropic peak broadening for both austenite and martensite. Since there is fine microstructure (
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