Lattice Rotation vs. Misorientation

[yixingx]

Hi everyone!

I’m studying plastic deformation and EBSD data analysis, but I’m a bit confused about the distinction between lattice rotation and misorientation. Could someone help clarify these concepts?

Any guidance, documentation references, or code snippets would be greatly appreciated! Thank you!

[zmichels]

A "misorientation" describes the misalignment of any two orientations (it's like a "difference" between pairs of orientations). The two orientations considered when computing a misorientation don't need to be spatially or kinematically linked.

However, if someone uses the term "lattice rotation", there is an implied kinematic and spatial/structural context. Likely the analysis is targeting orientations of material that has exhibit some intragranular lattice distortion (e.g., produced during crystalplastic deformation). When attempting to characterize lattice distortion, differences between pairs of orientations (misorientation) might be computed as part of an analysis. However, because a misorientation only applies to a single pair of orientations, consideration of grains-scale (or more macroscopic) kinematics will require some technique to more holistically analyze a set of orientations directly, or perform some meaningful treatment of many misorientations (e.g., one for every pair of considered orientations).

So, rotating/distorting a lattice will produce variation in orientations that can be quantified/characterized between any two points with a misorientation/rotation. However, "lattice rotation" is a concept/process that carries a genetic implication about the lattice history.

[zmichels]

Also... the terminology gets a bit muddy because mathematically an orientation is a rotation (it describes the position of material axes relative to a reference frame... as a rotation). So a single orientation is a rotation.

[yixingx]

Thank you for the explanation! I believe this resolves my confusion. I now understand how they differ conceptually and in practical analysis.

To confirm my understanding:
Gernerally,
Misorientation = orientation difference between any two points/parts.
Lattice rotation = orientation evolution (kinematic process is required).

Appreciate your time and expertise!

[kilir]

Hi,
I might say that a misorientation is a measure/description of a lattice rotation.
Cheers,
Rüdiger