Operando Mechanical Microscopy of Materials

The paper overviews the use of operando studies to characterise materials deformation at multiple scales reaching down to (sub)micron resolution. Within the range of techniques employed for this purpose, the use of electron and ion microscopies and X-ray scattering and imaging play a central role due to their versatility and availability. Digital Image Correlation (DIC) offers a robust, scalable and universally applicable means of deformation analysis that allows the determination of overall and local strain from continuously recorded micrographs of material surface. Further extensions and refinements of this method allows advancing this approach to 3D mapping, both in terms of in-plane and out-of-plane surface displacements, and in terms of volumetric mapping of displacements based on tomographic imaging. The inhomogeneity of deformation and strain localisation represent essential insights needed to determine the onset of localisation and the progression towards failure. Wide Angle and Small Angle X-ray scattering (WAXS/SAXS) are powerful techniques of structure and deformation analysis across the scales. These methods will be demonstrated in application to a variety of materials including metals, ceramics, polymers and composites.