On Recent Advances in Microstructural Characterization and In-Situ Testing Techniques to Study Material Behavior

The deformation fields within grains in polycrystalline materials are generally highly heterogeneous and can be the precursors to the nucleation of micro-cracks or cavities. Such behavior is conditioned by microstructural features, such as grain structure, texture, morphology, and size. The understanding of the inter-relationship between the material’s microstructural characteristics and complex deformation and damage phenomena is crucial to the formulation of structural integrity assessments of engineering components, since they constitute the physical bases of the required constitutive models of deformation and failure.

In this work, an overview is provided of recent experimental techniques developed at ONERA and elsewhere to characterize the microstructure and to measure the deformation of metallic materials. Some of the most promising characterization, measurement and identification techniques and methods used to develop, calibrate and validate physicsinspired constitutive models will be discussed, and illustrative examples will be given. It will be shown that the individual use of traditional interferometric, characterization and testing techniques is being replaced by the combined use of state-of-the-art techniques based on image correlation (2D and 3D), in-situ and ex-situ scanning electronic microscopy (SEM), EBSD, amongst others. Discussions about future trends, including the great potential offered by the combination of in-situ techniques at various scales with real time computations, are presented.