Recently, I carried out the EBSD experiments on Al-20Si.
However, the quality of the Kikuchi pattern of sample surface was good but the low calibration rate in EBSD system was obtained. It is so hard for the EBSD equipment to distinguish aluminium between silicon. I found that these two materials are different structures and lattice constants. So is there someone who can tell me what caused this problem.
Thank you very much.
Dear Zhang
I had have this problem, too. there are some references hinting the reasons of this question, "Why EBSD cannot distinguish the aluminum and silicon in Al-Si alloy".
the lattice of Si is diamond structure which follows the face-centered cubic (FCC) Bravais lattice and the lattice of Al is FCC. Actually, owing to proximity of atomic number of Si and Al as well as similarity of the cubic lattice of them, the microstructure of silicon merges with the microstructure of Al.
I can send you some references about that.
Please feel free to contact me if you have any questions.
If the crystallographyc details given by Esmaeil Damavandi are right (I think so), then the only differences between the diffractions of these systems will be on the exclusion patern of some Kikuchi bands due to their specific atoms positions.
Light elements like Al and Si have also poor backscattering that decreases the intensity of diffraction signal, this detail together and the proximity of diffraction pattern of the systems turn out to be a bad situation for phase identification.
Their weight proximity make the differentiation by backscattering quality using indexes like image quality, MAD, and so on, also a hard task for the softwares.
Usually EBSD systems use Hogh transformation to estimate crystal orientations and not identify phases. This detail cannot be negleted during the experimental design.
However, this phase identification is not impossible.
I recomend you to look at the Kikuchi patterns of these phases and try to figure out a image analysis method for phase identification. If you do that, it worths a publication already.
Dear Esmaeil Damavandi
Thank you so much for your answer. I used a combined EBSD-EDS technology for the phase identification in Al-Si alloy. The orientations in this alloy seem to be normal, but the phase distribution was totally mismarked at first.
So many thanks for your kind help.
Dear Davison Ramos de Almeida Junior
Thanks for your answer. I reviewed the standard Kikuchi patterns of Al and Si and found that these patterns are totally different. I have not viewed the real-time patterns collected during EBSD experiment. Based on your suggestion, the patterns would be collected.
Thanks again for your suggestion.
Dear Zhang,
You're welcome.
I would like to know what is your mean about saying this sentence " the phase distribution was totally mismarked at first"?
Sorry for my improper expression Dr. Esmaeil Damavandi ,
During EBSD process, we found that Al and primary Si phase were indistinguishable despite the different lattice structures and constants (displayed follows). Therefore, we used a technology combined the EBSD patterns and EDS signals to distinguish these two phases and detailed microstructure evolution processes were unriddled by this technology.
Figures are attached to this response. Thank you so much.
Yongyun Zhang
Yes. According to your images, the combination EBSD patterns and EDS signals, which you had used, is not suitable and the phase identification has been not done correctly.
Regarding to my experiences, I suggest you to use EDS analysis before or after EBSD test. For this alloy and similar Al-Si alloys, you can use the EDS to identify the phases and distinguish Si phase from Al phase.
It noteworthy to say that when the magnification of SEM increases, you have to pay attention to shifting phenomena. sometimes, this mismatch, can be related to this reason.
Meanwhile, you can use the KAM (Kernel Average Mis-orientation) maps to identify the Si phase. Owing to brittle manner of Si particles, these particles show blue color in KAM maps, however, the deformed Al grains have yellow color. this is a general description.
If you want, I can send you some images related to EDS, KAM and EBSD to further explanation.
Best regards
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