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atomistic simulation study of favored compositions of Ni-Nb-Al metallic glasses

Science China(Technological Sciences) 2018年第12期61卷 1829-1838页

作者： CAI Bei YANG MengHao LIU JianBo LI JiaHao LIU BaiXin Key Laboratory of Advanced Materials(MOE) School of Materials science and Engineering Tsinghua University

This study investigates the formation process of Ni-Nb-Al metallic glasses. To this end, a long-range n-body potential was constructed for the Ni-Nb-Al ternary metal system, and applied to atomistic simulations. The simulations not only showed the physical origins of the amorphous phase formation, but also quantitatively predicted a hexagonal compositional region that energetically favors the glass formation. The energy difference between the solid solution and metallic glass, which generates the amorphization driving force(ADF), was suggested to indicate the glass-formation ability(GFA) of each alloy. Based on the computed ADFs, the Ni55 Nb25 Al20 alloy exhibited the highest GFA among the Ni-Nb-Al members, implying that the glass formed by this amorphous alloy is more thermodynamically stable than other alloys in the system. In a Voronoi tessellation analysis, the knee point of the coordination-number distribution curve corresponded to the glass-formation region of the Ni-NbAl system.

关键词： interatomic potential atomistic simulation glass-formation ability Ni-Nb-Al system

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atomistic Failure Mechanism of Single Wall Carbon Nanotubes with Small Diameters

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Chinese Physics Letters 2007年第1期24卷 165-168页

作者：纪冬高翔孔向阳李家明 Department of Physics Shanghai Jiao Tong University Shanghai 200240 Department of Materials Science and Engineering Shanghai diao Tong University Shanghai 200240 The Key Laboratory of Atomic and Molecular Nanosciences Department of Physics Tsinghua University Beijing 100084

Single wall carbon nanotubes with small diameters （〈 5.0 A） subjected to bending deformation are simulated by orthogonal tight-binding molecular dynamics approach. Based on the calculations of C-C bond stretching and breaking in the bending nanotubes, we elucidate the atomistic failure mechanisms of nanotube with small diameters. In the folding zone of bending nanotube, a large elongation of C-C bonds occurs, accounting for the superelastic behaviour. The C-C bonds parallel to the axis direction of nanotube are broken firstly due to the sustained longitudinal stretching strain, giving rising to forming one-notch or two-notch bond-breaking mode depending on nanotube chirMities. The direct bond-breaking mechanism is responsible for the brittle fracture behaviour of nanotubes with small diameters.

关键词： atomistic Small Diameters Physics Failure Mechanism

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Revealing the Effects of Pore Size and Geometry on the Mechanical Properties of Graphene Nanopore Using the atomistic Finite Element Method

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Acta Mechanica Solida Sinica 2019年第1期32卷 81-92页

作者： Prapasiri Pongprayoon Attaphon Chaimanatsakun Department of Chemistry Faculty of ScienceKasetsart UniversityChatuchakBangkok 10900Thailand Center for Advanced Studies in Nanotechnology for Chemical Food and Agricultural IndustriesKU Institute for Advanced StudiesKasetsart UniversityBangkok 10900Thailand Computational Biomodelling Laboratory for Agricultural Science and Technology(CELAST) Kasetsart UniversityBangkok 10900Thailand Department of Mechanical Engineering Faculty of Engineering at SrirachaKasetsart UniversityTungsukhlaSrirachaChonburi 20230Thailand

Graphene nanopore has been extensively employed in nanoscale sensing devices due to its outstanding *** understanding of its mechanical properties at nanoscale is crucial for sensing *** this work,the mechanical proper ties of graphene nanopore are t hus investigated using the atomistic finite element met *** graphene models with different pore shapes(circle(CR),horizontal rec tangle(RH),vertical rec tangle(RV)and square(SQ))in sub-5nm size,which could be successfully fabricated experimentally,have been studied *** force normal to a pore rim is applied to mimic the impact force due to a fluid *** expected,the strength of nanoholed graphene is pore size *** pore size results in the reduction in its str *** bet ween different pore shapes with comparable sizes,the order of pore st rength is CR>RH>RV>*** addition,two different corner st rue tu res(V-like or zigzag and C-like or armchair corners)are observed,where the V-like st rue ture causes higher tensile ***,we find that the highest tensile stress is produced at the corner in all *** finding suggests the corners as an origin of pore *** results of RH and RV highlight the impact of a direction of pore orientation on mechanical *** a long side of a pore along the zigzag direction gains more tensile stress,while aligning on an armchair side causes a *** only the pore geometry and size,but also the pore orientation is crucial for defining the mechanical properties of nanopores.

关键词： Nanopores atomistic finite element Graphene nanopores Nanosensors

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In situ atomistic observation of disconnection-mediated grain boundary migration

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Science Foundation in China 2019年第1期27卷 16-16页

Under the support of the National Natural Science Foundation of China,the research team led by *** Ze(张泽)and *** JiangWei(王江伟)at the Center of Electron Microscopy and State Key Laboratory of Silicon Materials,School of Materials Science and Engineering,Zhejiang University,revealed the atomistic mechanism of disconnection-mediated grain boundary migrations in metallic nanostructures,which was published in Nature Communications(2019,10:156).

关键词： In situ atomistic observation disconnection-mediated boundary migration

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Effect of Cr Doping on the Surface Characteristics of Ni Metal Studied with First-Principles Calculation

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Acta Metallurgica Sinica(English Letters) 2019年第4期32卷 461-470页

作者： Xian-Feng Sun Hai-Tao Wang En-Hou Han CAS Key Laboratory of Nuclear Materials and Safety Assessment Institute of Metal ResearchChinese Academy of Sciences School of Materials Science and Engineering University of Science and Technology of China

The influence of Cr doping on the surface characteristics of Ni metal, including the surface energy, work function,adsorption and dissociation, has been investigated by means of first-principles calculation based on density functional theory. The results reveal that with the increase in Cr doping amount, the surface energies for all(111),(110) and(100)surfaces increase, whereas the work functions of(111) and(100) surfaces decrease followed by an increase and that of(110) surface has been decreasing. On the typical Ni(111) and Ni-Cr(111) surfaces, the adsorption energies follow the sequence O > OH > H > H_2O, and the doping of Cr increases the chemical activity of surfaces leading to the improvement of adsorption energies. The H_2O dissociating to OH and H is easier than the subsequent OH dissociating to O and H. The addition of Cr into Ni surface decreases the energy barriers and significantly increases the reaction rate constants.

关键词： Density functional theory Surface characteristics Nickel Cr addition atomistic simulation

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