title: Nanodomained Nickel Unite Nanocrystal Strength with Coarse-Grain Ductility.
abstract: Conventional metals are routinely hardened by grain refinement or by cold working with the expense of their ductility. Recent nanostructuring strategies have attempted to evade this strength versus ductility trade-off, but the paradox persists. It has never been possible to combine the strength reachable in nanocrystalline metals with the large uniform tensile elongation characteristic of coarse-grained metals. Here a defect engineering strategy on the nanoscale is architected to approach this ultimate combination. For Nickel, spread-out nanoscale domains (average 7 nm in diameter) were produced during electrodeposition, occupying only ~2.4% of the total volume. Yet the resulting Ni achieves a yield strength approaching 1.3 GPa, on par with the strength for nanocrystalline Ni with uniform grains. Simultaneously, the material exhibits a uniform elongation as large as ~30%, at the same level of ductile face-centered-cubic metals. Electron microscopy observations and molecular dynamics simulations demonstrate that the nanoscale domains effectively block dislocations, akin to the role of precipitates for Orowan hardening. In the meantime, the abundant domain boundaries provide dislocation sources and trapping sites of running dislocations for dislocation multiplication, and the ample space in the grain interior allows dislocation storage; a pronounced strain-hardening rate is therefore sustained to enable large uniform elongation.
authors.affiliation: State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China.
authors.forename: Xiaolei
authors.initials: X
authors.lastname: Wu
authors.affiliation: State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China.
authors.forename: Fuping
authors.initials: F
authors.lastname: Yuan
authors.affiliation: State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China.
authors.forename: Muxin
authors.initials: M
authors.lastname: Yang
authors.affiliation: State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China.
authors.forename: Ping
authors.initials: P
authors.lastname: Jiang
authors.affiliation: State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China.
authors.forename: Chuanxin
authors.initials: C
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China.
authors.forename: Liu
authors.initials: L
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China.
authors.forename: Yueguang
authors.initials: Y
authors.lastname: Wei
authors.affiliation: Department of Materials Science and Engineering, The Johns Hopkins University, Baltimore, Maryland 21218, USA.
authors.forename: Evan
authors.initials: E
authors.lastname: Ma