We present a quantitative, multiscale, four-dimensional study of ductile damage evolution during a "tension-to-shear" load path change in a recrystallized AA2198-T851 alloy sheet. Significant strain and damage develop under tension, and their subsequent evolution under shear is quantified. Damage mechanisms are characterized using synchrotron-based in situ 3D X-ray laminography, complemented by correlative surface imaging. Mesoscale strain fields, measured via projection digital image correlation and validated through simulations, guide the selection of representative regions of interest and their boundary conditions for detailed microscale analysis within the sample bulk. Damage features are either grain-related or intermetallic particle-induced. Grain-related damage shows only moderate evolution under shear, with volume increases of a factor one and a half, whereas intermetallic particle-induced voids exhibit pronounced growth, with volume increases up to factor of six. To elucidate the underlying mechanism, experimentally observed particle-void clusters are investigated using three-dimensional finite element modeling initialized with measured boundary conditions. The simulations reproduce the strong shear-driven void growth via a void-locking mechanism associated with stiff intermetallic particles. In their absence, simulations predict a strongly reduced void growth under shear, confirming the critical role of intermetallic particles in shear-driven damage evolution.

The dislocation evolution in a cross-section a-plane cut through a sublimation-grown aluminum nitride (AlN) crystal grown with low-temperature gradients and subsequent low thermal stress is investigated with different X-ray diffraction imaging methods. Exploiting the so-called weak-beam contrast using monochromatic X-rays in combination with suitable three-dimensional (3D) interpretation and reconstruction allows the identification of individual dislocations as well as tracing their progression in the crystal volume, even in the considerably strained interface region. It is particularly striking that the laterally grown crystal volume is dislocation-free. The dislocation densities in the seed and the bulk volume are similar (1 x 103 cm-2), but while the dislocations in the seed are randomly arranged, the dislocations in the bulk volume show a uniform line shape, indicating a common mechanism of dislocation movement. Since the dislocation slings in the bulk do not lie in slip planes, it can be concluded that the lateral movement does not result from dislocation glide, but from impurity-driven climb of dislocations during growth. The absence of slip can be explained by the low-temperature gradients and the subsequent low thermal stress below the critical resolved shear stress (CRSS).

Bent crystals can be used to deflect high-energy charged particles for beam extraction and/or beam collimation at accelerator facilities, thanks to the channelling phenomenon. In the present paper, two perfect silicon mono-crystals were bent using two different methods: sandblasting and the application of a carbon fibre composite. In particular, these samples were obtained for the realization of bent crystal prototypes to be used to steer the 7 TeV proton beam of the Large Hadron Collider in the context of the CRYSBEAM project. The two bending methods were selected since they allow a very homogeneous curvature of the crystals to be obtained, which is essential for high channelling efficiency. Moreover, the deformation obtained is self-standing, i.e. there is no need for any external device to keep the samples bent. Self-standing curvature can be useful because the presence of an external bender could be a severe limitation in the collider beam-pipe. The curvature of the samples was measured through high-energy X-ray diffraction at the ID11 beamline of the European Synchrotron Radiation Facility in Grenoble, France. Since the diffraction efficiencies obtained were in good agreement with theoretical expectations, it follows that the manufacturing techniques did not damage the samples, i.e. the crystallographic quality was preserved. Finally, the crystal quality of the sandblasted sample was investigated in detail at the synchrotron source at Karlsruhe Institute of Technology by X-ray white-beam topography. The measurements showed no diffusion of defects from the machined surfaces to the crystal bulk.

This article describes complete characterization of the polygonal dislocation half-loops (PDHLs) introduced by scratching and subsequent bending of an Si(111) crystal. The study is based on the X-ray topo-tomography technique using both a conventional laboratory setup and the high-resolution X-ray image-detecting systems at the synchrotron facilities at KIT (Germany) and ESRF (France). Numerical analysis of PDHL images is performed using the Takagi–Taupin equations and the simultaneous algebraic reconstruction technique (SART) tomographic algorithm.

1 Karlsruhe Institute of Technology (KIT), Institute for Photon Science and Synchrotron Radiation (IPS/ANKA), 76344 Eggenstein, Germany 2 Karlsruhe Institute of Technology (KIT), Laboratory for Applications of Synchrotron Radiation (LAS), 76344 Eggenstein, Germany 3 University Freiburg, Crystallography, Institute for Geosciences, 79104 Freiburg, Germany 4 European Synchrotron Radiation Facility (ESRF), F-38043 Grenoble, France