In this section we consider the analysis of twining. Therefore lets start by importing some Magnesium data and reconstructing the grain structure.
Next we extract the grain boundaries and save them to a separate variable
The output tells us that we have 3219 Magnesium to Magnesium boundary segments and 606 boundary segments where the grains are cut by the scanning boundary. To restrict the grain boundaries to a specific phase transition you shall do
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
We observe that we have many grain boundaries with misorientation angle larger than 80 degree. In order to investigate the distribution of misorientation angles further we have the look at a misorientation angle histogram.
Lets analyze the misorientations corresponding to the peak around 86 degree in more detail. Therefore, we consider only those misorientations with misorientation angle between 85 and 87 degree
and observe that when plotted in axis angle domain they form a strong cluster close to one of the corners of the domain.
We may determine the center of the cluster and check whether it is close to some special orientation relation ship
Bases on the output above we may now define the special orientation relationship as
and observe that it is actually a rotation about axis (-1210) and angle 86.3 degree
Next, we check for each boundary segment whether it is a twinning boundary, i.e., whether boundary misorientation is close to the twinning.
A common next step is to reconstruct the grain structure parent to twinning by merging the twinned grains. This is explained in detail in the section Merging Grains.