The role of electron-beam irradiation on small-scale deformation: Challenges and benefits in in situ SEM indentation tests

Abstract

In situ mechanical testing has led to a huge development and increase in our scientific insights in the small-scale deformation behavior of many material systems. The in situ mechanical testing approaches were enabled via the advance of modern nanomechanical testing systems, such as nanoindenters, as well as microfabrication techniques, such as focus ion-beam systems. Particular micropillar compression experiments have led to the famous smaller-is-stronger phenomena in crystalline materials or smaller is more ductile for amorphous materials, like glasses. However, as in the case of focused ion-beam sample preparation, in situ observation with an active electron beam can lead to additional and not apparent effects on the material behavior, which needs to be carefully considered. Electron-beam irradiation-induced athermal viscous flow has been observed in silica glass, even on the micron scale while there are also reports on crystalline materials showing electron-beam-dependent plastic deformability. In this regard, this article aims providing a critical assessment of electron-beam influences upon testing inside an electron microscope to shed yet another light on smaller-is-stronger/softer statements. Moreover, the article will also emphasize the potential of the electron beam to trigger unique room-temperature properties with high potential for local micro-forming in some material classes.Graphical abstractElectron irradiation induces aa Brittle-Ductile-Transition (BDT) via a local activation of flow processes