Kui Du

University of Otago

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Scott X. Mao

Zhejiang University

Christopher R. Weinberger

Colorado State University

Jianyu Huang

Yanshan University

Liyuan Sheng

University of Hong Kong

Zhenhua Zhang

Institute of Coal Chemistry

Guoxian Li

Hebei University of Technology

A. Trampert

Paul Drude Institute for Solid State Electronics

K. H. Ploog

National Sun Yat-sen University

K. Kash

Case Western Reserve University

Shiqiang Wei

University of Science and Technology of China

Cooperative Institutions

Chinese Academy of Sciences

University of Science and Technology of China

University of Chinese Academy of Sciences

Beijing University of Technology

Institute of Metals Research

Centre National de la Recherche Scientifique

Shanghai Jiao Tong University

Zhejiang University

Central South University

Case Western Reserve University

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Model and experiments for bistatic scattering strength of underwater objects

Guangli Cheng Mingmin Zhang Kui Du Wan-jun Yao

Model of bistatic scattering strength of underwater object in the far field is set up by Kirchhoff approximation. Monostatic target strength (TS) of Generic BeTSSi-submarine versus azimuthal angles are calculated by the proposed method at 1 kHz, 4 kHz and 8 kHz, which agree well with the international well-known data, and the computational accuracy is enhanced with the increment of acoustic frequency, and the proposed model is also useful even if the frequency is lower to 1 kHz. Bistatic scattering strength of Generic BeTSSi-submarine and the steady state echo waves from CW and LFM signals are predicted, which show agreement with experimental results, and demonstrate that the proposed model can be used to predict the bistatic scattering strength of large underwater objects.

Target strength

Underwater acoustic communication

10.1109/iccasm.2010.5622985

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In situ atomic-scale observation of grain size and twin thickness effect limit in twin-structural nanocrystalline platinum

Nature Communications (2020)

Lihua Wang Kui Du Chengpeng Yang Jiao Teng Libo Fu

Abstract Twin-thickness-controlled plastic deformation mechanisms are well understood for submicron-sized twin-structural polycrystalline metals. However, for twin-structural nanocrystalline metals where both the grain size and twin thickness reach the nanometre scale, how these metals accommodate plastic deformation remains unclear. Here, we report an integrated grain size and twin thickness effect on the deformation mode of twin-structural nanocrystalline platinum. Above a ∼10 nm grain size, there is a critical value of twin thickness at which the full dislocation intersecting with the twin plane switches to a deformation mode that results in a partial dislocation parallel to the twin planes. This critical twin thickness value varies from ∼6 to 10 nm and is grain size-dependent. For grain sizes between ∼10 to 6 nm, only partial dislocation parallel to twin planes is observed. When the grain size falls below 6 nm, the plasticity switches to grain boundary-mediated plasticity, in contrast with previous studies, suggesting that the plasticity in twin-structural nanocrystalline metals is governed by partial dislocation activities.

Nanocrystalline material

Deformation mechanism

Severe Plastic Deformation

Grain boundary strengthening

10.1038/s41467-020-14876-y

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Deformation-induced structural transition in body-centred cubic molybdenum

Nature Communications (2014)

Shoujun Wang Hao Wang Kui Du W. Zhang Manling Sui

Molybdenum is a refractory metal that is stable in a body-centred cubic structure at all temperatures before melting. Plastic deformation via structural transitions has never been reported for pure molybdenum, while transformation coupled with plasticity is well known for many alloys and ceramics. Here we demonstrate a structural transformation accompanied by shear deformation from an original <001>-oriented body-centred cubic structure to a <110>-oriented face-centred cubic lattice, captured at crack tips during the straining of molybdenum inside a transmission electron microscope at room temperature. The face-centred cubic domains then revert into <111>-oriented body-centred cubic domains, equivalent to a lattice rotation of 54.7°, and ~15.4% tensile strain is reached. The face-centred cubic structure appears to be a well-defined metastable state, as evidenced by scanning transmission electron microscopy and nanodiffraction, the Nishiyama–Wassermann and Kurdjumov–Sachs relationships between the face-centred cubic and body-centred cubic structures and molecular dynamics simulations. Our findings reveal a deformation mechanism for elemental metals under high-stress deformation conditions. Structural phase transitions are known to accommodate plastic deformation in some metals and ceramics. Here, the authors observe the in situtransformation of body-centred cubic molybdenum to face-centred cubic, and finally to body-centred cubic, allowing for 15.4% tensile strain accommodation.

Cubic crystal system

Metastability

10.1038/ncomms4433

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Water induced ultrathin Mo2C nanosheets with high-density grain boundaries for enhanced hydrogen evolution

Nature Communications (2022)

Yang Yang Yumin Qian Zhaoping Luo Haijing Li Lanlan Chen

Grain boundary controlling is an effective approach for manipulating the electronic structure of electrocatalysts to improve their hydrogen evolution reaction performance. However, probing the direct effect of grain boundaries as highly active catalytic hot spots is very challenging. Herein, we demonstrate a general water-assisted carbothermal reaction strategy for the construction of ultrathin Mo2C nanosheets with high-density grain boundaries supported on N-doped graphene. The polycrystalline Mo2C nanosheets are connected with N-doped graphene through Mo-C bonds, which affords an ultra-high density of active sites, giving excellent hydrogen evolution activity and superior electrocatalytic stability. Theoretical calculations reveal that the dz2 orbital energy level of Mo atoms is controlled by the MoC3 pyramid configuration, which plays a vital role in governing the hydrogen evolution activity. The dz2 orbital energy level of metal atoms exhibits an intrinsic relationship with the catalyst activity and is regarded as a descriptor for predicting the hydrogen evolution activity.

10.1038/s41467-022-34976-1

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Discrete plasticity in sub-ten-nanometer-sized Au crystals.

Nature Communications (2010)

Jianyu Huang Christopher R. Weinberger Cao Ajing Kui Du Jiaxu Wang

Nanometre

Crystal Plasticity

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Transition of dislocation nucleation induced by local stress concentration in nanotwinned copper

Nature Communications (2015)

Ning Lü Kui Du Lei Lu H. Q. Ye

Abstract Metals with a high density of nanometre-scale twins have demonstrated simultaneous high strength and good ductility, attributed to the interaction between lattice dislocations and twin boundaries. Maximum strength was observed at a critical twin lamella spacing (∼15 nm) by mechanical testing; hence, an explanation of how twin lamella spacing influences dislocation behaviours is desired. Here, we report a transition of dislocation nucleation from steps on the twin boundaries to twin boundary/grain boundary junctions at a critical twin lamella spacing (12–37 nm), observed with in situ transmission electron microscopy. The local stress concentrations vary significantly with twin lamella spacing, thus resulting in a critical twin lamella spacing (∼18 nm) for the transition of dislocation nucleation. This agrees quantitatively with the mechanical test. These results demonstrate that by quantitatively analysing local stress concentrations, a direct relationship can be resolved between the microscopic dislocation activities and macroscopic mechanical properties of nanotwinned metals.

Lamella (surface anatomy)

10.1038/ncomms8648

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Citations (130)

Continuous and reversible atomic rearrangement in a multifunctional titanium alloy

Materialia (2018)

Yu Hao D.L. Gong Tong Li H. Wang Julie M. Cairney

Pseudoelasticity

Titanium alloy

Diffusionless transformation

Spinodal decomposition

Poisson's ratio