title: Strain Hardening and Size Effect in Five-fold Twinned Ag Nanowires.
abstract: Metallic nanowires usually exhibit ultrahigh strength but low tensile ductility owing to their limited strain hardening capability. Here we study the unique strain hardening behavior of the five-fold twinned Ag nanowires by nanomechanical testing and atomistic modeling. In situ tensile tests within a scanning electron microscope revealed strong strain hardening behavior of the five-fold twinned Ag nanowires. Molecular dynamics simulations showed that such strain hardening was critically controlled by twin boundaries and pre-existing defects. Strain hardening was size dependent; thinner nanowires achieved more hardening and higher ductility. The size-dependent strain hardening was found to be caused by the obstruction of surface-nucleated dislocations by twin boundaries. Our work provides mechanistic insights into enhancing the tensile ductility of metallic nanostructures by engineering the internal interfaces and defects.
authors.affiliation: †Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States.
authors.forename: Sankar
authors.initials: S
authors.lastname: Narayanan
authors.affiliation: ‡Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, North Carolina 27695, United States.
authors.forename: Guangming
authors.initials: G
authors.lastname: Cheng
authors.affiliation: †Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States.
authors.forename: Zhi
authors.initials: Z
authors.lastname: Zeng
authors.affiliation: ‡Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, North Carolina 27695, United States.
authors.forename: Yong
authors.initials: Y
authors.lastname: Zhu
authors.affiliation: †Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States.|§School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States.
authors.forename: Ting
authors.initials: T
authors.lastname: Zhu
keywords: Nanowire; in situ experiment; molecular dynamics; size effects; strain hardening; twin boundary