title: Reversal in the Size Dependence of Grain Rotation.
abstract: The conventional belief, based on the Read-Shockley model for the grain rotation mechanism, has been that smaller grains rotate more under stress due to the motion of grain boundary dislocations. However, in our high-pressure synchrotron Laue x-ray microdiffraction experiments, 70 nm nickel particles are found to rotate more than any other grain size. We infer that the reversal in the size dependence of the grain rotation arises from the crossover between the grain boundary dislocation-mediated and grain interior dislocation-mediated deformation mechanisms. The dislocation activities in the grain interiors are evidenced by the deformation texture of nickel nanocrystals. This new finding reshapes our view on the mechanism of grain rotation and helps us to better understand the plastic deformation of nanomaterials, particularly of the competing effects of grain boundary and grain interior dislocations.
authors.affiliation: Center for High Pressure Science and Technology Advanced Research, Pudong, Shanghai 201203, China.|Advanced Light Source, Lawrence Berkeley National Lab, Berkeley, California 94720, USA.
authors.forename: Xiaoling
authors.initials: X
authors.lastname: Zhou
authors.affiliation: Advanced Light Source, Lawrence Berkeley National Lab, Berkeley, California 94720, USA.
authors.forename: Nobumichi
authors.initials: N
authors.lastname: Tamura
authors.affiliation: Center for High Pressure Science and Technology Advanced Research, Pudong, Shanghai 201203, China.
authors.forename: Zhongying
authors.initials: Z
authors.lastname: Mi
authors.affiliation: Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, USA.
authors.forename: Jialin
authors.initials: J
authors.lastname: Lei
authors.affiliation: Advanced Light Source, Lawrence Berkeley National Lab, Berkeley, California 94720, USA.
authors.forename: Jinyuan
authors.initials: J
authors.lastname: Yan
authors.affiliation: Center for High Pressure Science and Technology Advanced Research, Pudong, Shanghai 201203, China.
authors.forename: Lingkong
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Center for High Pressure Science and Technology Advanced Research, Pudong, Shanghai 201203, China.
authors.forename: Wen
authors.initials: W
authors.lastname: Deng
authors.affiliation: Center for High Pressure Science and Technology Advanced Research, Pudong, Shanghai 201203, China.
authors.forename: Feng
authors.initials: F
authors.lastname: Ke
authors.affiliation: Center for High Pressure Science and Technology Advanced Research, Pudong, Shanghai 201203, China.
authors.forename: Binbin
authors.initials: B
authors.lastname: Yue
authors.affiliation: Center for High Pressure Science and Technology Advanced Research, Pudong, Shanghai 201203, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Chen