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Pervasive deformation twinning in magnesium greatly affects its strength and formability. The local stress fields associated with twinning play a key role on deformation behavior and fracture but are extremely difficult to characterize experimentally. In this study, we perform synchrotron experiments with differential-aperture X-ray microscopy to measure the 3D stress fields in the vicinity of a twin with a spatial resolution of 0.5 micrometer. The measured local stress field aids to identify the sequence of events involved with twinning. We find that the selected grain deforms elastically before twinning, and the twin formation splits the grain into two non-interacting domains. Under further straining one domain of the grain continued to deform elastically, whereas the other domain deforms plastically by prismatic slip. This heterogeneous deformation behavior may be mediated by the surrounding medium and it is likely to lead to asymmetric twin growth.

The distribution of elastic strains (and thus stresses) at the submicrometre length scale within deformed metal single crystals has remarkably broad implications for our understanding of important physical phenomena. These include the evolution of the complex dislocation structures that govern mechanical behaviour within individual grains, the transport of dislocations through such structures, changes in mechanical properties that occur during reverse loading (for example, sheet-metal forming and fatigue), and the analyses of diffraction line profiles for microstructural studies of these phenomena. We present the first direct, spatially resolved measurements of the elastic strains within individual dislocation cells in copper single crystals deformed in tension and compression along <001> axes. Broad distributions of elastic strains are found, with important implications for theories of dislocation structure evolution, dislocation transport, and the extraction of dislocation parameters from X-ray line profiles.

The crystallographic texture of thin-film coatings plays an essential role in determining such diverse materials properties as wear resistance, recording density in magnetic media and electrical transport in superconductors. Typically, X-ray pole figures provide a macroscopically averaged description of texture, and electron backscattering provides spatially resolved surface measurements. In this study, we have used focused, polychromatic synchrotron X-ray microbeams to penetrate multilayer materials and simultaneously characterize the local structure, orientation and strain tensor of different heteroepitaxial layers with submicrometre resolution. Grain-by-grain microstructural studies of cerium oxide films grown on textured nickel foils reveal two distinct kinetic growth regimes on vicinal surfaces: ledge growth at elevated temperatures and island growth at lower temperatures. In addition, a combinatorial approach reveals that crystallographic tilting associated with these complex interfaces is qualitatively described by a simple geometrical model applicable to brittle films on ductile substrates. The sensitivity of conducting percolation paths to tilt-induced texture improvement is demonstrated.