EBSD Tutorial
+ +A quick guide on how to import and make basic plots with EBSD data in MTEX.
+ +Data import
+MTEX allows you to import EBSD from all big vendors of EBSD systems. Prefered data formats are text based data files like .ang, .ctf or open binary formats like .osc or .h5. Most conveniently, EBSD data may be imported using the import wizard, by typing
or by the command EBSD.load
+ +or by the command EBSD.load +
{% highlight matlab %} %load some test data packaged with your MTEX installation fileName = [mtexDataPath filesep 'EBSD' filesep 'Forsterite.ctf']; @@ -26,6 +41,11 @@ {% endhighlight %} {% highlight plaintext %} +Warning: .ctf files have usualy inconsistent conventions for spatial +coordinates and Euler angles. You may want to use one of the options +'convertSpatial2EulerReferenceFrame' or +'convertEuler2SpatialReferenceFrame' to correct for this + ebsd = EBSD Phase Orientations Mineral Color Symmetry Crystal reference frame @@ -39,14 +59,19 @@ X x Y x Z : [0 36550] x [0 16750] x [0 0] Normal vector: (0,0,1) {% endhighlight %} -This command outputs ebsd data stored in a single variable, called ebsd. This variable contains all relevant information, i.e., the spatial coordinates, the orientation information, a description of the crystal symmetries and all other parameters contained in the input data file.
Phase Plots
In this example, the output above shows that the data set contains three different phases: Forsterite, Enstatite, and Diopside. The spatial distribution of the different phases can be visualized by the plotting command
+This command outputs ebsd data stored in a single variable, called ebsd. This variable contains all relevant information, i.e., the spatial coordinates, the orientation information, a description of the crystal symmetries and all other parameters contained in the input data file.
Phase Plots
+In this example, the output above shows that the data set contains three different phases: Forsterite, Enstatite, and Diopside. The spatial distribution of the different phases can be visualized by the plotting command
{% highlight matlab %} plotx2east % this command tells MTEX to plot the x coordinates increasing to the east (left) plot(ebsd,'coordinates','on') {% endhighlight %}When importing EBSD data it is critically important to align it correctly to a fixed reference frame. This issue is exhaustively discussed in the topic Reference Frame Alignment.
Orientation Plots
Analyzing orientations of an EBSD map can be done only for each phase seperately. The key syntax to restrict the data to a single phase is
+ +When importing EBSD data it is critically important to align it correctly to a fixed reference frame. This issue is exhaustively discussed in the topic Reference Frame Alignment.
+Orientation Plots
+Analyzing orientations of an EBSD map can be done only for each phase separately. The key syntax to restrict the data to a single phase is
{% highlight matlab %} ebsd('Forsterite') {% endhighlight %} @@ -77,9 +102,12 @@ {% endhighlight %}In this standard form a default color coding of the orientations is choosen. A more complete discussion about how to colorize orientations can be found in the topic IPF Maps.
Grain reconstruction
MTEX contains a sophisticated algorithm for reconstructing the grain structure from EBSD data as described in the paper Grain detection from 2d and 3d EBSD data and the topic Grain Reconstruction. The syntax is
+ +In this standard form a default color coding of the orientations is chosen. A more complete discussion about how to colorize orientations can be found in the topic IPF Maps.
+Grain reconstruction
+MTEX contains a sophisticated algorithm for reconstructing the grain structure from EBSD data as described in the paper Grain detection from 2d and 3d EBSD data and the topic Grain Reconstruction. The syntax is
{% highlight matlab %} -% reconstruct grains with a theshold angle of 10 degrees +% reconstruct grains with a threshold angle of 10 degrees grains = calcGrains(ebsd('indexed'),'theshold',10*degree) % smooth the grains to avoid the staircase effect @@ -100,7 +128,7 @@ Properties: meanRotation, GOS {% endhighlight %} -This creates a variable grains of type grain2d which containes the full geometric information about all grains and their boundaries. As the simplest application we may just plot the grain boundaries
This creates a variable grains of type grain2d which contains the full geometric information about all grains and their boundaries. As the simplest application we may just plot the grain boundaries
Crystal Shapes
In order to make the visualization of crystal orientations more intuitive MTEX supports crystal shapes. Those are polyhedrons computed to match the typical shape of ideal crystals. In order to overlay the EBSD map with crystal shapes orienteted accordingly to the orientations of the grains we proceed as follows.
+ +Crystal Shapes
+In order to make the visualization of crystal orientations more intuitive MTEX supports crystal shapes. Those are polyhedrons computed to match the typical shape of ideal crystals. In order to overlay the EBSD map with crystal shapes oriented accordingly to the orientations of the grains we proceed as follows.
{% highlight matlab %} % define the crystal shape of Forsterite and store it in the variable cS cS = crystalShape.olivine(ebsd('Forsterite').CS) -% select only grains with more then 100 pixels -grains = grains(grains.grainSize > 100); +% select only Forsterite grains with more then 100 pixels +grains = grains('Forsterite',grains.grainSize > 100); % plot crystal shapes at the positions of the Forsterite grains hold on -plot(grains('Forsterite'),0.7*cS,'FaceColor',[0.3 0.5 0.3]) +plot(grains,0.7*cS,'colored') hold off {% endhighlight %} @@ -131,7 +161,9 @@ {% endhighlight %}Pole Figures
One of the most important tools for analysing the orientations in an EBSD map are pole figure plots. Those answer the question of how selected crystal directions, here h, are aligned with respect to specimen directions
Pole Figures
+One of the most important tools for analyzing the orientations in an EBSD map are pole figure plots. Those answer the question of how selected crystal directions, here h, are aligned with respect to specimen directions
Inverse Pole Figures
Analogously one can ask for the crystal directions pointing in a selected specimen direction. The resulting plots are called inverse pole figures.
+ +Inverse Pole Figures
+Analogously one can ask for the crystal directions pointing in a selected specimen direction. The resulting plots are called inverse pole figures.
{% highlight matlab %} % select the specimen direction r = vector3d.Z; @@ -162,4 +196,7 @@ {% endhighlight %}