For crystalline materials containing more than one phase, e.g. for mineralogical samples but also for some technical products like steel or Ti-Al, is it meaningful to display the microstructure by IPF or Euler colouring for all phases at the same time, or is it not required to generate single maps for at least all phases displayed by different colour keys?
I would want to see the orientation maps of each phase separately. For example in steel you can have a mixture of FCC and BCC phases which would have extremely different texture components. If they were plotted together it would be extremely misleading. For some materials, I have even separated orientation maps by grain size or elastic strain to look for correlations.
Thanks Lowrence. Good argument... This would make sense also in case of a bimodal microstructure which can (or perhaps commonly) also have another texture. At least it means, that a publication displaying IPF maps mixing all phase together should be actually "rejected" since this image is actually useless since one cannot see anything from the displayed colors (except in case of very specific textures) ?
Yes exactly. Things like bi-modal (or multi-modal) microstructures would be hidden. If I were reviewing a paper that only showed orientation maps or data that combined all phases, I would ask that they be split by phase before publication.
Yes, Volker. This I would count under the specific term "specific applications".But it is more the exeption, comparable to the application of non-standard settings for crystal structure descriptions. It more puzzles people than it helps, although under specific conditions it is really useful. The problem is that these data will be non-transformed implemented in data bases and "nobody" can simply use them anymore since the applied programs misinterprete them since they don't consider exceptations. Back to EBSD one should limit the display of IPF maps on single phases in software packages. There are other options like Photoshop for these very rare cases it prehaps make sense. But even there I am not sure whether two seperate images perhaps show this as well or even better.
Nowadays all EBSD data are usually displayed as IPF maps with the comment: "we always did this!"...although they probably changed from single to multiphase materials.
Dear Gert,
First of all, thanks a lot for your very good answer to my question in the field of EBSD data.
Coming back to your question, undoubtedly, you, Lawrence and Volker are expert in this field. I think same as you. I think for materials with more than one phases, it is necessary to separate the phases during working with EBSD software. Because, different phases have different microstructural features and textures. For example, if somebody is working on a double phase Ti alloy, he should analyze the texture of the different phases separately. if not, the result will not be understandable.
Dear Akbar, it should be in general hard to mix data assigned to different phases in EBSD software. Possible, but only with some "insider" tricks. But the major problem pointed out here is the orientation map display. It is impossible to mix orientation data in pole figures, but in map presentations it is. I wonder why? Only because it looks more beautiful? :-) I've never heard anybody complaining although we are entitled to do serious science. I can only speak for myself, but I doubt that I am able to clearly seperate information from different phases if they are mixed presented (except of extremely different and strong texture components). Then it is better to generate a new image since if we as "producer" of the maps already have difficulties, how an external person should be able to understand the sense (or nonsense) of such kind of presentation?
Following V.Klemm's argument, it is still desirable to have simultaneous mapping of both the phase and orientations (structure). A compromise is to get a phase map first (say bimodal blue-orange for two phases) and THEN superimpose on the latter a "boundary" map with tolerances 2, 4, 10 degs. Thus we will see distinctive substructural features on the background of distinct phases.
...and this is no orientation map anymore :-) what I was only talking about. And of course there is no reason why not to allow this option you described. I only wanted point out that a general display of color-coded orientation maps for multiphase materials (not preferably two well distinguishable) is actually quite useless. Not only if the symmetry is different...
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