Atomistic perspective on in situ nanomechanics

Abstract

Nanostructured materials exhibit superior physical and mechanical properties, and they hold great promise for enabling the development of novel micro/nano electromechanical systems. A fundamental understanding of the mechanical deformation and degradation in nanostructured materials is critical for designing the damage-tolerant nanostructures and devices. The in situ transmission electron microscopy provides a novel approach to uncover the dynamic deformation mechanisms in nanostructured materials, especially at the atomic scale. This review presents an overview of recent progress in the atomic-scale study of mechanical properties, dynamic deformation and degradation in a variety of nanostructured materials. Experimental techniques for in situ nanomechanical testing are reviewed. New insights into the atomic-level mechanical behavior of nanostructured materials are described, including surface-mediated defect processes, size-dependent deformation mechanisms, plastic deformation of nanotwinned and nanocrystalline materials, phase transformation, liquid-like behavior and pseudoelasticity, bending and fatigue, etc. Future research on the in situ nanomechanics is also discussed. Ultimately, the in situ nanomechanics study will enable a complete understanding of the atomic-scale dynamic deformation, thereby providing a mechanistic basis of the rational design and fabrication of durable nanomaterials and nanodevices.

Mechanics of Crystalline Nanowires: An Experimental Perspective

“…Similar to the method to create thin NWs in the AFM force spectroscopy, thin metal NWs were formed with stable contacts between a metal rod and a scanning tunneling microscope (STM) probe inside TEM, especially under applied voltage [107,108]. Stable contacts can also form between thin metal NWs inside TEM by cold welding [109].…”

In situ atomistic observation of disconnection-mediated grain boundary migration

“…Some experimental insights into the GB migration have been obtained in the past two decades, with the spring up of well-designed in situ transmission electron microscopy (TEM) techniques 10,20,21 . For example, in situ heating experiments have revealed a thermal-induced GB migration in Au and Al thin films at 0.4–0.7 T m ( T m is the melting temperature) through the atomic shuffling 22 or GB disconnection 23 mechanisms.…”

Effect of orientation and mode of loading on deformation behaviour of Cu nanowires

“…All these studies have shown that the important mechanisms of plastic deformation in FCC nanowires are slip through perfect and partial dislocations and deformation twinning. The competition between slip and twinning mechanisms depends mainly on the crystallographic orientation, size, shape and loading mode (tension/compression), temperature and strain rate [13,14,15]. However, among all these factors, crystallographic orientation has the strongest influence followed by mode of loading [12,13].…”