<i>In situ</i> nanomechanical testing in focused ion beam and scanning electron microscopes

TLDR

Recent interest in size‑dependent deformation of micro‑ and nanoscale materials has grown alongside technological miniaturization and advances in imaging and small‑scale mechanical testing methods. This work presents a quantitative in‑situ nanomechanical testing approach adapted to a dual‑beam focused ion beam and scanning electron microscope. The method employs a three‑plate capacitor transducer for high‑fidelity force and displacement measurement, manipulates and aligns specimens with a dual‑beam system and electron‑beam assisted Pt deposition, and records local strain using digital image correlation of electron images. Illustrative results from tensile testing of single‑crystalline metallic nanowires and compression of nanoporous Au pillars demonstrate size effects on mechanical behavior and reveal challenges of conducting nanomechanical testing in vacuum environments.

Abstract

The recent interest in size-dependent deformation of micro- and nanoscale materials has paralleled both technological miniaturization and advancements in imaging and small-scale mechanical testing methods. Here we describe a quantitative in situ nanomechanical testing approach adapted to a dual-beam focused ion beam and scanning electron microscope. A transducer based on a three-plate capacitor system is used for high-fidelity force and displacement measurements. Specimen manipulation, transfer, and alignment are performed using a manipulator, independently controlled positioners, and the focused ion beam. Gripping of specimens is achieved using electron-beam assisted Pt-organic deposition. Local strain measurements are obtained using digital image correlation of electron images taken during testing. Examples showing results for tensile testing of single-crystalline metallic nanowires and compression of nanoporous Au pillars will be presented in the context of size effects on mechanical behavior and highlight some of the challenges of conducting nanomechanical testing in vacuum environments.