Hardening in Au-Ag nanoboxes from stacking fault-dislocation interactions

Radhika P Patil; David Doan; Zachary H Aitken; Shuai Chen; Mehrdad T Kiani; Christopher M Barr; Khalid Hattar; Yong-Wei Zhang; X Wendy Gu

doi:10.1038/s41467-020-16760-1

Hardening in Au-Ag nanoboxes from stacking fault-dislocation interactions

Nat Commun. 2020 Jun 10;11(1):2923. doi: 10.1038/s41467-020-16760-1.

Authors

Radhika P Patil¹, David Doan¹, Zachary H Aitken², Shuai Chen², Mehrdad T Kiani³, Christopher M Barr⁴, Khalid Hattar⁴, Yong-Wei Zhang², X Wendy Gu⁵

Affiliations

¹ Department of Mechanical Engineering, Stanford University, Stanford, CA, 94305, USA.
² Institute of High Performance Computing, A*STAR, 1 Fusionopolis Way, #16-16 Connexis, Singapore, 138632, Singapore.
³ Department of Materials Science and Engineering, Stanford University, Stanford, CA, 94305, USA.
⁴ Materials, Physical, and Chemical Sciences, Sandia National Laboratories, Albuquerque, NM, 87185, USA.
⁵ Department of Mechanical Engineering, Stanford University, Stanford, CA, 94305, USA. xwgu@stanford.edu.

Abstract

Porous, nano-architected metals with dimensions down to ~10 nm are predicted to have extraordinarily high strength and stiffness per weight, but have been challenging to fabricate and test experimentally. Here, we use colloidal synthesis to make ~140 nm length and ~15 nm wall thickness hollow Au-Ag nanoboxes with smooth and rough surfaces. In situ scanning electron microscope and transmission electron microscope testing of the smooth and rough nanoboxes show them to yield at 130 ± 45 MPa and 96 ± 31 MPa respectively, with significant strain hardening. A higher strain hardening rate is seen in rough nanoboxes than smooth nanoboxes. Finite element modeling is used to show that the structure of the nanoboxes is not responsible for the hardening behavior suggesting that material mechanisms are the source of observed hardening. Molecular dynamics simulations indicate that hardening is a result of interactions between dislocations and the associated increase in dislocation density.