A disclination model for twinning and de-twinning of nanotwinned copper

Abstract

The twinning and de-twinning processes within grains of nanotwinned copper (nt-Cu) are schematically demonstrated using the concept of wedge disclination quadrupoles. The stable twin nucleus size and the equilibrium equation of the applied shear stress and twin width during twin growth are obtained. The dependence of the critical resolved shear stress for twinning on the grain size, which conforms to the classic Hall–Petch relationship, is theoretically modelled. Additionally, the disclination quadrupole model for de-twinning is used to interpret the strength softening in nt-Cu. Relative to the classic kinetic and energetic models, this novel approach is more compatible with the experiments.

Keywords:

• Twinning
• de-twinning
• disclination quadrupole
• nanotwinned copper

Funding

The work was supported by the National Natural Science Foundation of China [grant number 11402128], [grant number 11372103], [grant number 51475156],[grant number 11202110], [grant number [11472141]; the Science Fund of State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body [grant number 31315012]; the Zhejiang Provincial Natural Science Foundation of China [grant number LQ14A020001]; the Natural Science Foundation of Ningbo City [grant number 2013A610074]; the grant from the Mechanics Initiative, a COE Program of Zhejiang Provincial Government in the Department of Mechanics and Engineering Science, Ningbo University [grant number xklx1501], and the K. C. Wong Magna Fund from Ningbo University.