Grain Boundary Tutorial
A quick guide to grain boundary analysis
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Grain boundaries generation |
Properties of grain boundaries |
Grain boundaries generation
To work with grain boundaries we need some ebsd data and have to detect grains within the data set.
% load some example data mtexdata twins % detect grains [grains,ebsd.grainId,ebsd.mis2mean] = calcGrains(ebsd('indexed')) % smooth them grains = grains.smooth % visualize the grains plot(grains,grains.meanOrientation)
grains = grain2d Phase Grains Pixels Mineral Symmetry Crystal reference frame 1 121 22833 Magnesium 6/mmm X||a*, Y||b, Z||c* boundary segments: 3825 triple points: 114 Properties: GOS, meanRotation ebsd = EBSD Phase Orientations Mineral Color Symmetry Crystal reference frame 0 46 (0.2%) notIndexed 1 22833 (100%) Magnesium light blue 6/mmm X||a*, Y||b, Z||c* Properties: bands, bc, bs, error, mad, x, y, grainId, mis2mean Scan unit : um ebsd = EBSD Phase Orientations Mineral Color Symmetry Crystal reference frame 0 46 (0.2%) notIndexed 1 22833 (100%) Magnesium light blue 6/mmm X||a*, Y||b, Z||c* Properties: bands, bc, bs, error, mad, x, y, grainId, mis2mean Scan unit : um grains = grain2d Phase Grains Pixels Mineral Symmetry Crystal reference frame 1 121 22833 Magnesium 6/mmm X||a*, Y||b, Z||c* boundary segments: 3825 triple points: 114 Properties: GOS, meanRotation I'm going to colorize the orientation data with the standard MTEX colorkey. To view the colorkey do: oM = ipfColorKey(ori_variable_name) plot(oM)

Now we can extract from the grains its boundary and save it to a seperate variable
gB = grains.boundary
gB = grainBoundary Segments mineral 1 mineral 2 606 notIndexed Magnesium 3219 Magnesium Magnesium
The output tells us that we have 3219 Magnesium to Magnesium boundary segments and 606 boundary segements where the grains are cutted by the scanning boundary. To restrict the grain boundaries to a specific phase transistion you shall do
gB_MgMg = gB('Magnesium','Magnesium')
gB_MgMg = grainBoundary Segments mineral 1 mineral 2 3219 Magnesium Magnesium
Properties of grain boundaries
A variable of type grain boundary contains the following properties
- misorientation
- direction
- segLength
These can be used to colorize the grain boundaries. By the following command we plot the grain boundaries colorized by the misorientation angle
plot(gB_MgMg,gB_MgMg.misorientation.angle./degree,'linewidth',2)
mtexColorbar

hold on plot(gB('notIndexed'),'lineColor','blue','linewith',5) hold off

grains.innerBoundary
ans = grainBoundary Segments mineral 1 mineral 2 4 Magnesium Magnesium
MTEX 5.2.beta1 |