PNNL

Abstract

Advances in the use of in situ transmission electron microscopy (TEM) to study mechanical deformation have enabled a direct correlation of mechanical properties with microstructures, in particular, atomic-level defect dynamic processes. Shear deformation of metallic materials has been noticed to lead to unique microstructural features with superior properties that would be difficult to achieve by traditional metallurgical processes. However, in contrast to the case of in situ TEM studies of structural evolution under tension, compression, and bending, in situ TEM probing of dynamic processes during direct shear loading, especially at microscales and nanoscales, is very limited. This paper reviews recent progress on the development of in situ TEM for studying shear deformation in terms of both the technique and the scientific insights that have been gained. In addition, we discuss current challenges encountered in the use of in situ TEM for shear deformation, such as the limited total strain, strain rate, and spatial and temporal resolution. To provide perspective, we present promising opportunities for in situ TEM studies with pure shear loading by taking advantage of the integration of advanced imaging techniques both in TEM and scanning transmission electron microscopy domains, advanced electron detectors, highly efficient chemical analysis, data-driven machine learning, and environmental conditions.