Journal Article

Slip-activated surface creep with room-temperature super-elongation in metallic nanocrystals

Zhang, Ze, Zhong, Li, Wang, Chongmin, Mao, Scott X., Sansoz, Frederic, He, Yang

2017

Overview

Nanoscale metallic crystals have been shown to follow a ‘smaller is stronger’ trend. However, they usually suffer from low ductility due to premature plastic instability by source-limited crystal slip. Here, by performing in situ atomic-scale transmission electron microscopy, we report unusual room-temperature super-elongation without softening in face-centred-cubic silver nanocrystals, where crystal slip serves as a stimulus to surface diffusional creep. This interplay mechanism is shown experimentally and theoretically to govern the plastic deformation of nanocrystals over a material-dependent sample diameter range between the lower and upper limits for nanocrystal stability by surface diffusional creep and dislocation plasticity, respectively, which extends far beyond the maximum size for pure diffusion-mediated deformation (for example, Coble-type creep). This work provides insight into the atomic-scale coupled diffusive–displacive deformation mechanisms, maximizing ductility and strength simultaneously in nanoscale materials. In situ atomic-scale imaging of deformation in silver nanocrystals reveals that it is possible to achieve deformability and high strength, attributed to a coupling mechanism between crystal slip and surface diffusional creep.

• Publisher: Nature Publishing Group UK,Nature Publishing Group
• Subject: 639/301/1023/303 / 639/301/357 / Biomaterials / Condensed Matter Physics / Creep (materials) / Crystals / Deformation mechanisms / Dependent sample / Diffusion / Dislocations / Ductility / Elongation / Environmental Molecular Sciences Laboratory / Materials Science / Nanocrystals / Nanotechnology / Optical and Electronic Materials / Plastic deformation / Plastic instability / Room temperature / Silver / Slip / Stability / Surface stability / Transmission electron microscopy