3D/4D imaging of complex and deformed microstructures with pink-beam dark field X-ray microscopy.

Abstract

Dark Field X-ray Microscopy (DFXM) has advanced 3D non-destructive, high-resolution imaging of strain and orientation in crystalline materials, enabling the study of embedded structures in bulk. However, the photon-hungry nature of monochromatic DFXM limits its applicability for studying highly deformed or weakly crystalline structures, and constrains time-resolved studies in industrially relevant materials. Here, we present pink-beam DFXM (pDFXM) at the ID03 beamline of ESRF, achieving a 27-fold increase in diffracted intensity while maintaining 100 nm spatial resolution. We validate pDFXM by imaging a partially recrystallized aluminum grain, confirming sufficient angular resolution for microstructure mapping. The increased flux significantly enhances the diffracted signal, enabling the resolution of subgrain structures. Additionally, we image a highly deformed ferritic iron grain, previously inaccessible in monochromatic mode without focusing optics. Beyond static imaging, pDFXM enables real-time tracking of grain growth during annealing, achieving hundred-millisecond temporal resolution. By combining high photon flux with non-destructive, high-resolution 3D mapping, pDFXM expands diffraction-contrast imaging to poorly diffracting crystals, unlocking new opportunities for studying grain growth, fatigue, and corrosion in bulk materials.