In situ and tomographic characterization of damage and dislocation processes in irradiated metallic alloys by transmission electron microscopy

Abstract

Progress toward combining time-resolved experiments with periodic three-dimensional analysis of the evolved microstructural state has been made recently. In situ electron microscopy is used to observe in real time the development of irradiation defects and the influence of these defects on dislocation behavior. Three-dimensional characterization provides information on the true spatial distribution of defects and clarifies effects of the free surfaces in thin films. This quasi-four dimensional analysis approach has been applied to understand the formation of channels in irradiated alloys, the depth distribution of ion damage in an electron transparent foil, and the dislocation channel interactions with grain boundaries. The new insight obtained from these experiments is highlighted and contrasted with findings from simulations.

Fundamental Mechanisms for Irradiation-Hardening and Embrittlement: A Review

“…(5) Defect is sheared by dislocations and remains as a single one or is broken into small ones [111,113,115,116]. These experimental observations could help verify the fundamental mechanisms observed in numerical simulations, and also provide insights into the formation of defect-free channels in irradiated materials [117].…”

Three-Dimensional Atomic Structure of Grain Boundaries Resolved by Atomic-Resolution Electron Tomography

“…It is generally accepted that the mobility of kinks and jogs controls the mobility of dislocations. 45,[53][54][55] Also, interactions between kinks and jogs will influence the glide process of dislocations. In our simulations, during shear deformation of the GB with jogs, kinks will also initiate from the existing jogs to facilitate GB dislocation migration.…”

Conditions near a crack tip: Advanced experiments for dislocation analysis and local strain measurement

“… 52 , 57 , 59 Observation of crack tips in metallic specimens during tensile deformation provides direct insight into dislocation emission mechanisms. 60 This not only allows the investigation of the type and spatial configuration of dislocations that are emitted from the crack tip, but through their curvature even local friction stresses can be estimated. 61 Thin-foil effects leading to local thinning and dislocation escape have to be taken into account when analyzing the crack propagation.…”