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| 1 | Surface removal of a copper thin film in an ultrathin water environment by a molecular dynamics study显示文摘The surface planarity and asperity removal behavior on atomic scale in an ultrathin water environment were studied for a nanoscale process by molecular dynamics simulation.Monolayer atomic removal is achieved under both noncontact and monoatomic layer contact conditions with different water film thicknesses.The newly formed surface is relatively smooth without deformed layers,and no plastic defects are present in the subsurface.The nanoscale processing is governed by the interatomic adhering action during which the water film transmits the loading forces to the Cu surface and thereby results in the migration and removal of the surface atoms.When the scratching depth≥0.5 nm,the abrasive particle squeezes out the water film from the scratching region and scratches the Cu surface directly.This leads to the formation of trenches and ridges,accumulation of chips ahead of the particles,and generation of dislocations within the Cu substrate.This process is mainly governed by the plowing action,leading to the deterioration of the surface quality.This study makes the'0 nm planarity,0 residual defects,and 0 polishing pressure'in a nanoscale process more achievable and is helpful in understanding the nanoscale removal of materials for developing an ultra-precision manufacture technology. | Junqin SHI Liang FANG Kun SUN Weixiang PENG Juan GHEN Meng ZHANG | 2020 | Friction2020，8，2： | 3 |
| 2 | Nanostructured Anode Materials for Non-aqueous Lithium Ion Hybrid Capacitors显示文摘The rapid advancement in electronic devices,electric vehicles,and grid storage stations have lead to a high demand for energy storage devices with enhanced power and energy densities as well as extended lifespans.Lithium ion hybrid capacitors are constructed with battery-type anodes and capacitor-type cathodes,which enables the direct integration of the high energy from lithium ion batteries and high power and long lifetime from supercapacitors,making lithium ion hybrid capacitor one of the most promising energy storage devices.In the past two decades,tremendous efforts have been put into the search for suitable battery-type anode materials with improved Faradaic reaction kinetics so that it can match with the fast non-Faradaic charging rate of the capacitive cathodes.This review aims to provide an up-to-date and comprehensive summary of the battery-type anode materials for high-performance lithium ion hybrid capacitors.To date,a large variety of battery-type anode materials have been explored with smart material design strategies,such as carbonaceous materials,metal oxides,alloys,sulfides,nitirdes,and Mxenes,etc.,which will be discussed in detail.A perspective to the challenges and future developing trends of lithium ion hybrid capacitors is proposed to close. | Cuiping Han Hongfei Li Ruiying Shi Lei Xu Junqin Li Feiyu Kang Baohua Li | 2018 | Energy & Environmental Materials2018，1，2： | 3 |
| 3 | Formation mechanism of hierarchical twins in the CoCrNi medium entropy alloy显示文摘The three-dimensional hierarchical twin network has been proved to be the source of the excellent strength-ductility combination in the CoCrNi medium entropy alloy.Revealing the formation mechanism of hierarchical twins,however,remains a challenge using either the post-mortem or the in-situ microstructural characterization.In this study,the atomistic formation mechanism of hierarchical twins was investigated using molecular dynamics simulations,with special focus on the effects of strain rate and deformation temperature.Compared to the primary twin boundaries kink-driven hierarchical twinning tendency in pure FCC metals,the chemical inhomogeneity in CoCrNi can reduce the necessary kink height to trigger conjugate twins(CTWs),fascinating the formation of twin networks.At room temperature,the plastic deformation is dominated by primary twins(PTWs)and conjugate slips at a relatively lower strain rate(e.g.,5×10^(7)s^(−1)).The hierarchical twins can be activated in cases of deforming at a higher strain rate(e.g.,2×10^(8)s^(−1)).Further increasing the strain rate(e.g.,1×10^(10) s^(−1))leads to the phase-transformation induced plasticity.At cryogenic temperatures,the hierarchical twins are promoted within a large range of strain rates(e.g.,5×10^(7)–1×10^(10) s^(−1)).A higher temperature leads to the synergy of CTWs and primary slips at a lower strain rate,but hierarchical twins at a higher strain rate.On this basis,a qualitative comparison and scalable trends between experiments and simulations were revealed.The present study would not only provide the basic understanding for the twinning behavior found experimentally,but also contribute to the design of medium/high entropy alloys with excellent mechanical performances by tuning microstructures. | Dongpeng Hua Xiaorong Liu Wan Wang Qing Zhou Qiaosheng Xia Shuo Li Junqin Shi Haifeng Wang | 2023 | Journal of Materials Science & Technology2023，，9： | 0 |
| 4 | Molecular dynamics simulation of the tribological performance of amorphous/amorphous nano-laminates显示文摘Because the amorphous/amorphous nano-laminates could enhance signifcantly the mechanical properties of the amorphous materials,they have been widely studied as a new group of structural materials.In this study,the nano-scratch performance of the Cu_(80)Zr_(20)/Cu_(20)Zr_(80)(A/B-type)and the Cu_(20)Zr_(80)/Cu_(80)Zr_(20)(B/A-type)amorphous/amorphous nano-laminates was evaluated by molecular dynamics simulation.Their dependences on the type of indenter,layer thickness,stacking mode and scratch depth were systematically analyzed.There is a signifcant size effect for the tribological properties of amorphous/amorphous nanolaminates that the friction force of the A/B-type increases with the increase of layer thickness,but the friction force of the B/A-type decreases as the layer thickness increase.The interface has an obvious obstruction effect on the shear deformation and reduces the plastic affected region below the scratched groove.Particularly,the contact environment of the indenter bottom has an important influence on the normal force,so it’s not that the deeper the depth,the greater the normal force.Hence it should not be ignored when evaluating the tribological properties of the amorphous/amorphous nano-laminates.This work can deepen the understanding of hetero-interface on the deformation mechanism during nano-scratch,and help to design amorphous nano-laminates with tailored tribological performance for practical applications. | Dongpeng Hua Wan Wang Dawei Luo Qing Zhou Shuo Li Junqin Shi Maosen Fu Haifeng Wang | 2022 | Journal of Materials Science & Technology2022，，10： | 0 |
| 5 | Movement pattern of an ellipsoidal nanoparticle confined between solid surfaces: Theoretical model and molecular dynamics simulation显示文摘The movement pattern of ellipsoidal nanoparticles confined between copper surfaces was examined using a theoretical model and molecular dynamics simulation.Initially,we developed a theoretical model of movement patterns for hard ellipsoidal nanoparticles.Subsequently,the simulation indicated that there are critical values for increasing the axial ratio,driving velocity of the contact surface,and lowering normal loads(i.e.,0.83,15 m/s,and 100 nN under the respective conditions),which in turn change the movement pattern of nanoparticles from sliding to rolling.Based on the comparison between the ratio of arm of force(e/h)and coefficient of friction(μ),the theoretical model was in good agreement with the simulations and accurately predicted the movement pattern of ellipsoidal nanoparticles.The sliding of the ellipsoidal nanoparticles led to severe surface damage.However,rolling separated the contact surfaces and thereby reduced friction and wear. | Junqin SHI Xiangzheng ZHU Kun SUN Liang FANG | 2021 | Friction2021，9，5： | 0 |
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