title: Recoverable plasticity in penta-twinned metallic nanowires governed by dislocation nucleation and retraction.
abstract: There has been relatively little study on time-dependent mechanical properties of nanowires, in spite of their importance for the design, fabrication and operation of nanoscale devices. Here we report a dislocation-mediated, time-dependent and fully reversible plastic behaviour in penta-twinned silver nanowires. In situ tensile experiments inside scanning and transmission electron microscopes show that penta-twinned silver nanowires undergo stress relaxation on loading and complete plastic strain recovery on unloading, while the same experiments on single-crystalline silver nanowires do not exhibit such a behaviour. Molecular dynamics simulations reveal that the observed behaviour in penta-twinned nanowires originates from the surface nucleation, propagation and retraction of partial dislocations. More specifically, vacancies reduce dislocation nucleation barrier, facilitating stress relaxation, while the twin boundaries and their intrinsic stress field promote retraction of partial dislocations, resulting in full strain recovery.
authors.affiliation: Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, North Carolina 27695, USA.
authors.forename: Qingquan
authors.initials: Q
authors.lastname: Qin
authors.affiliation: School of Engineering, Brown University, Providence, Rhode Island 02912, USA.
authors.forename: Sheng
authors.initials: S
authors.lastname: Yin
authors.affiliation: Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, North Carolina 27695, USA.
authors.forename: Guangming
authors.initials: G
authors.lastname: Cheng
authors.affiliation: Centre of Advanced Mechanics and Materials, Applied Mechanics Laboratory, Department of Engineering Mechanics, Tsinghua University, Beijing 100084, China.
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Li
authors.affiliation: Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, North Carolina 27695, USA.
authors.forename: Tzu-Hsuan
authors.initials: TH
authors.lastname: Chang
authors.affiliation: Max Planck Institute for Intelligent Systems, Heisenbergstrasse 3, D-70589 Stuttgart, Germany.
authors.forename: Gunther
authors.initials: G
authors.lastname: Richter
authors.affiliation: Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, North Carolina 27695, USA.
authors.forename: Yong
authors.initials: Y
authors.lastname: Zhu
authors.affiliation: School of Engineering, Brown University, Providence, Rhode Island 02912, USA.
authors.forename: Huajian
authors.initials: H
authors.lastname: Gao