  Over past decades, high energy X-ray diffraction techniques at synchrotron
beamline offer us the unique possibility to follow concomitantly some
mechanisms on the grain level in metallic materials. Crystal rotation, as one
important factor for the crystal orientation distribution, usually influences
the anisotropic properties of materials. Crystal rotation has been visualized
in deformation, recrystallization, and chemical reaction processes. In this
study, we firstly visualized an unexpected crystal rotation during heating up
of superalloys as well by in situ 3DXRD scanning microscopy which has not been
previously reported yet. The crystal rotation was found to be related to the
locked-in first order residual strain relief during the annealing treatment. In
addition, intermittent dynamic, i.e., some individual diffraction spots from
Debye-Scherrer rings appearing, disappearing, and reappearing, occurred in this
study which has ever been thought to be caused by subgrain formation in
deformation experiments. However, by residual strain analysis coupled with
finite element simulation, we found that the intermittent dynamic is married
with thermal expansion, crystal distortion, and crystal rotation as well. This
finding opens a new world for deeply understanding the residual strain relief
during materials, particularly metal, heating.
