In this section we explain how to extract specific grain boundaries. Therefore we start by importing some EBSD data and reconstructing the grain structure.
close all; plotx2east
% import the data
mtexdata forsterite silent
% restrict it to a subregion of interest.
ebsd = ebsd(inpolygon(ebsd,[5 2 10 5]*10^3));
[grains,ebsd.grainId] = calcGrains(ebsd('indexed'));
% remove very small grains
ebsd(grains(grains.grainSize <= 5)) = [];
% and recompute grains
[grains,ebsd.grainId] = calcGrains(ebsd('indexed'));
% smooth the grains a bit
grains = smooth(grains,4);
% visualize as a phase map
plot(ebsd)
hold on
plot(grains.boundary,'linewidth',2)
hold off
![](images/BoundarySelect_01.png)
The output of
grains.boundary
ans = grainBoundary
Segments length mineral 1 mineral 2
439 27383 µm notIndexed Forsterite
18 1550 µm notIndexed Enstatite
22 1350 µm notIndexed Diopside
1386 55740 µm Forsterite Forsterite
656 26512 µm Forsterite Enstatite
519 20575 µm Forsterite Diopside
35 1296 µm Enstatite Enstatite
112 4828 µm Enstatite Diopside
28 1251 µm Diopside Diopside
tells us the number of boundary segments between the different phsaes. Those segments with notIndexed phase include also those boundary segments where the grains are cutted by the scanning boundary. To restrict the grain boundaries to a specific phase transistion you shall do
hold on
plot(grains.boundary('Fo','Fo'),'lineColor','blue','micronbar','off','lineWidth',2)
hold off
![](images/BoundarySelect_02.png)
Similarly we may select all Forsterite to enstatite boundary segements.
hold on
plot(grains.boundary('Fo','En'),'lineColor','darkgreen','micronbar','off','lineWidth',2)
hold off
![](images/BoundarySelect_03.png)
Note, that the order of the phase names matter when considering the corresponding misorintations
grains.boundary('Fo','En').misorientation(1)
grains.boundary('En','Fo').misorientation(1)
ans = misorientation (Forsterite → Enstatite)
Bunge Euler angles in degree
phi1 Phi phi2
239.986 50.6875 124.673
ans = misorientation (Enstatite → Forsterite)
Bunge Euler angles in degree
phi1 Phi phi2
55.3267 50.6875 300.014
In the fist case the misorientation returned is from Forsterite to Enstatite and in the second case its exactly the inverse
The selection of grain boundaries according to specific misorientationsm according to twist / tild character or twinning is explained in linked sections.