42 results on '"Shaopeng Pan"'
Search Results
2. The Structural Evolution of Al86Ni9La5 Glassy Ribbons during Milling at Room and Cryogenic Temperatures
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Zhicheng Yan, Yan Liu, Shaopeng Pan, Yihua Hu, Jing Pang, and Weimin Wang
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metallic glass ,milling ,crystallization ,structural rejuvenation ,shear band ,Technology ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Microscopy ,QH201-278.5 ,Descriptive and experimental mechanics ,QC120-168.85 - Abstract
Melt-spun metallic Al86Ni9La5 glassy ribbons solidified at different circumferential speeds (Sc) were subjected to high-energy ball milling at room and cryogenic temperatures. Crystallization induced by milling was found in the Al86Ni9La5 solidified at lower circumferential speed (Sc = 14.7 m/s), while the Al86Ni9La5 with Sc = 36.6 m/s kept amorphous. Besides, a trend of structural rejuvenation during milling process was observed, as the onset temperatures (Tx1, Tx2) and the crystallization enthalpies (ΔH1, ΔH2) first decreased and then increased along with the milling time. We explored the structural origin of crystallization by ab initio molecular dynamic simulations and found that the tricapped trigonal prism (TTP) Ni-centered clusters with a higher frequency in samples solidified at a lower cooling rate, which tend to link into medium-range orders (MROs), may promote crystallization by initiating the shear bands during milling. Based on the deformation mechanism and crush of metallic glasses, we presented a qualitative model to explain the structural rejuvenation during milling.
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- 2018
- Full Text
- View/download PDF
3. Related Structure Characters and Stability of Structural Defects in a Metallic Glass
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Xiaofeng Niu, Shidong Feng, and Shaopeng Pan
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metallic glass ,quasi-nearest atom ,molecular dynamics simulations ,Technology ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Microscopy ,QH201-278.5 ,Descriptive and experimental mechanics ,QC120-168.85 - Abstract
Structural defects were investigated by a recently proposed structural parameter, quasi-nearest atom (QNA), in a modeled Zr50Cu50 metallic glass through molecular dynamics simulations. More QNAs around an atom usually means that more defects are located near the atom. Structural analysis reveals that the spatial distribution of the numbers of QNAs displays to be clearly heterogeneous. Furthermore, QNA is closely correlated with cluster connections, especially four-atom cluster connections. Atoms with larger coordination numbers usually have less QNAs. When two atoms have the same coordination number, the atom with larger five-fold symmetry has less QNAs. The number of QNAs around an atom changes rather frequently and the change of QNAs might be correlated with the fast relaxation metallic glasses.
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- 2018
- Full Text
- View/download PDF
4. Low Profile Dynamic Patch Antenna Array With High-Intensity Radiation Fields (HIRF) Protection
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Ming Xu, Jibin Liu, Shaopeng Pan, Bowen Deng, Jihong Zhang, Zhaofeng Wu, Peiguo Liu, and Mingtuan Lin
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Computer Networks and Communications ,Automotive Engineering ,Aerospace Engineering ,Electrical and Electronic Engineering - Published
- 2022
5. Tri-polarization Reconfigurable Fabry-Perot Resonator Antenna in Ku-band
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Shichao Zhu, Jiagang He, Jie Yu, Yang Feng, Shaopeng Pan, and Gaosheng Li
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Astronomy and Astrophysics ,Electrical and Electronic Engineering - Abstract
In this paper, a broadband tri-polarization reconfigurable antenna applied to polarization diversity is proposed. A partially reflective surface (PRS) is designed to form an air-filled resonator cavity. The reflection phase of the PRS has a positive phase gradient in order to achieve the characteristics of the proposed antenna gain enhancement in the wideband. A metal patch of a four-arm meander structure is used as the radiation structure and the feeding is realized through a four-channel rotating feeding network with equal amplitude and 90∘ phase difference. The feeding network is connected to the radiation structure through four metallized vias. In order to realize the polarization reconfigurability, the PIN diodes and the corresponding DC bias circuit are integrated in the rotating feeding network. The characteristics of horizontal polarization (HP), vertical polarization (VP) and right-hand circular polarization (RHCP) are realized by changing the ON/OFF states of PIN diodes integrated in the feeding network. In order to verify the performance of the proposed antenna, fabrication and testing were carried out. The measurement results show that the -10 dB impedance bandwidths of HP, VP, RHCP are 11% (12.5-14 GHz), 6.4% (13.7-14.6 GHz) and 20% (12.2-14.9 GHz), and the peak realized gains are 9.1, 9.2 and 11.5 dBi, respectively. For RHCP mode, the 3-dB axial ratio bandwidth reaches about 17% (12.35-13.4 GHz and 13.6-14.9 GHz).
- Published
- 2023
6. Performance enhancement for antipodal Vivaldi antenna modulated by a high-permittivity metasurface lens
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Shaopeng Pan, Mingtuan Lin, Lin Qi, Pan Chen, Yang Feng, and Gaosheng Li
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Computer Networks and Communications ,Hardware and Architecture ,Signal Processing ,Electrical and Electronic Engineering - Published
- 2021
7. Ultra-wideband Flexible Implantable Antenna for Wireless Capsule Endoscopy System with Performance Improvement
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Gaosheng Li, Pan Chen, Shaopeng Pan, and Yang Feng
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business.industry ,Computer science ,Coplanar waveguide ,Bandwidth (signal processing) ,Electrical engineering ,Wireless Medical Telemetry Service ,Ultra-wideband ,Astronomy and Astrophysics ,Split-ring resonator ,Miniaturization ,Wireless ,Electrical and Electronic Engineering ,Antenna (radio) ,business - Abstract
The implantable antenna is an important part of the wireless capsule endoscopy (WCE) system to achieve wireless communication. This paper designed an ultra-wideband flexible implantable antenna for wireless capsule endoscopy system. With a very wide bandwidth, the antenna can completely cover the industrial, scientific, and medical frequency bands (ISM, 2.4-2.48 GHz) and Wireless Medical Telemetry Service (WMTS, 1.395-1.4 GHz). The expanded size of the proposed antenna is 18mm× 10mm× 0.1mm. The conformal technology of the antenna has further reduced the space of the system and achieved miniaturization. The capsule antenna in this paper is a compact planar monopole antenna fed by a coplanar waveguide, and it uses a flexible material as a dielectric substrate to achieve the conformal shape of the antenna. U-shaped ground branch (UGB) and a loaded split ring resonator (SRR) structure were used to further improve the antenna performance. Simulation and measurement results were basically the same. On the premise of radiation safety and miniaturization of the antenna, the ultra-wideband operation of the antenna was realized. This antenna design provided reference value for the design and application of the capsule antenna.
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- 2021
8. Computer Experiments on Self-diffusion Coefficients of Some Liquid Metals
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Shaopeng Pan, Jingyu Qin, Jin Wang, Xinxin Li, and Qiqi Sun
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010302 applied physics ,Self-diffusion ,Materials science ,Coordination number ,0211 other engineering and technologies ,Metals and Alloys ,Thermodynamics ,02 engineering and technology ,Condensed Matter Physics ,Atomic packing factor ,Computer experiment ,01 natural sciences ,Condensed Matter::Soft Condensed Matter ,Calculated data ,0103 physical sciences ,Metallic materials ,Materials Chemistry ,021102 mining & metallurgy - Abstract
The available experimental self-diffusion coefficients of twenty-two liquid elements near their melting temperatures are compared with the calculated data by the first-principal dynamics simulation. The holistic evaluation shows that the calculated self-diffusion coefficients are in reasonable agreement with the experimental data. For liquid metals with loose-packed structure, the self-diffusion coefficient decreases in general with the increase of packing fraction. For liquid metals with close-packed structure in which the coordination number is larger than 11.5, the self-diffusion coefficient fluctuates around 2.0×10-9 m2s-1, except for liquid Al, Ti and Li of which the self-diffusion coefficients are anomalously large. The packing fraction can only partially account for the self-diffusion coefficient of liquid metals.
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- 2021
9. A new criterion for glass-forming ability based on both devitrification and solidification processes
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Ji Wang, Yingdan Liu, Frédéric Affouard, Zijing Li, Li-Min Wang, Suhong Zhang, Shidong Feng, Shaopeng Pan, Yanshan University [Qinhuangdao], Taiyuan University of Technology, Unité Matériaux et Transformations - UMR 8207 (UMET), Institut de Chimie du CNRS (INC)-Institut National de la Recherche Agronomique (INRA)-Centre National de la Recherche Scientifique (CNRS)-Université de Lille-Ecole Nationale Supérieure de Chimie de Lille (ENSCL), and Centrale Lille-Institut de Chimie du CNRS (INC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)
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010302 applied physics ,Materials science ,Mechanical Engineering ,Kinetics ,Metals and Alloys ,Thermodynamics ,02 engineering and technology ,General Chemistry ,Liquidus ,021001 nanoscience & nanotechnology ,01 natural sciences ,Glass forming ,Crystallization temperature ,Condensed Matter::Soft Condensed Matter ,Devitrification ,Glass forming ability ,Metallic glass ,Mechanics of Materials ,0103 physical sciences ,Materials Chemistry ,[PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci] ,Time-temperature-transformation ,0210 nano-technology ,Glass transition - Abstract
International audience; Based on the time-temperature-transformation interpretation, a new criterion for glass forming ability, Z = [(Tx-Tg)/(Tl-Tg)][(Tl–Tl(c))/(Tl-Tg)]0.556, is proposed, where Tg, Tx, Tl and Tl(c) respectively denote the glass transition temperature, the onset crystallization temperature upon heating, the liquidus temperature and the onset solidification temperature of the liquid upon cooling. The Z parameter jointly considers the stability of the liquid and the devitrification of glassy phases. A non-linear relationship between the parameter Z and the critical glassy size dc has been found to be log (dc)cal = 0.1392 + 17.0616Z - 41.985(Z)2, showing stronger correlation than other earlier reported parameters. The advantage of using Z as a GFA parameter is that it roughly reflects the relative influences of the thermodynamics and kinetics of the systems on glass formation. In addition, the parameter describes the stability of liquid in the course of being quenched from above liquidus temperature.
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- 2021
10. Bond-breaking analyses on the characteristics of flow defects in metallic glasses under plastic deformation
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Junwei Qiao, Weimin Wang, Jingyu Qin, Xiaofeng Niu, Shaopeng Pan, and Guangping Zheng
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Amorphous metal ,Materials science ,Condensed matter physics ,Mechanical Engineering ,Metals and Alloys ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Curvature ,01 natural sciences ,0104 chemical sciences ,Amorphous solid ,Bond length ,Molecular dynamics ,Deformation mechanism ,Shear (geology) ,Mechanics of Materials ,Quadrupole ,Materials Chemistry ,0210 nano-technology - Abstract
Bond breaking related with plastic deformation in a deformed metallic glass Zr50Cu50 is investigated by molecular dynamics simulations. The results show that the spatial distributions of broken bonds are closely correlated with local shear strains, and the clustering behaviors of atoms with broken bonds (flow defects) are characterized with different stages of plastic deformation. The average distance among those clusters of flow defects decreases as the strains increase, which follows the curvature quadrupole model for flow defects in ideal amorphous solids. For the first time, the features of bond breaking processes are quantitatively measured with the chemical composition, bond length and orientation, bond pairs, local five-fold symmetry and quasi-nearest atoms, whose threshold values are important factors that could characterize the flow defects in metallic glasses under plastic deformation. The shape, orientation and energetics of flow defects quantitatively characterized by the bond breaking analysis thus facilitate our understanding on the deformation mechanisms in metallic glasses.
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- 2019
11. Preparation of bulk metallic glasses by modifying local structure of icosahedral quasicrystals
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Maozhi Li, Suhong Zhang, Riping Liu, Yongjun Tian, Shaopeng Pan, Shidong Feng, Zijing Li, and Li-Min Wang
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010302 applied physics ,Amorphous metal ,Materials science ,Condensed matter physics ,Precipitation (chemistry) ,Icosahedral symmetry ,Mechanical Engineering ,Metals and Alloys ,Ab initio ,Quasicrystal ,02 engineering and technology ,General Chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Metal ,Crystal ,Mechanics of Materials ,visual_art ,Phase (matter) ,0103 physical sciences ,Materials Chemistry ,visual_art.visual_art_medium ,0210 nano-technology - Abstract
An attempt is carried out to design metallic glasses by modifying the local structure of icosahedral quasicrystals. A series of metallic glasses are prepared by introducing beryllium to the quasicrystal former, Zr40Ti40Ni20, and the maximum diameter of the glasses reaches 20 mm. A phase transformation diagram is constructed for the alloys of (Zr40Ti40Ni20)100-xBex, revealing the transition from stable crystal to quasicrystal and then to metallic glasses with the increased Be content. This study shows a connection between the formation of metallic glasses and the specific thermodynamics of the initially precipitated quasicrystals. Interestingly, both improvements in the forming ability for glasses and quasicrystals are observed over a wide composition range. Ab initio molecular dynamic simulations show the evolution of the structural features of the metallic melts for the optimised glass forming region, which guarantee the primary precipitation of quasicrystal.
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- 2019
12. Hydrogenation properties of five-component Mg60Ce10Ni20Cu5X5 (X= Co, Zn) metallic glasses
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Zhongliang Ma, Shaopeng Pan, M. Gao, Huaijun Lin, Wei Li, Cheng Xu, Liquan Li, Xiaohui Hu, Yuying Meng, and Yunfeng Zhu
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010302 applied physics ,Materials science ,Amorphous metal ,Component (thermodynamics) ,Mechanical Engineering ,Kinetics ,Metals and Alloys ,02 engineering and technology ,General Chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Hydrogen atmosphere ,Distribution function ,Mechanics of Materials ,0103 physical sciences ,Materials Chemistry ,Physical chemistry ,0210 nano-technology ,Chemical composition - Abstract
Hydrogenation properties of two five-component Mg60Ce10Ni20Cu5X5 (X = Co, Zn) metallic glasses have been studied. Using high-pressure differential scanning calorimetery (HP-DSC) under hydrogen atmosphere and hydrogenation kinetics study, it is demonstrated that alloying with Zn shows negligible impact on the hydrogenation kinetics and storage capacity of the Mg Ce Ni Cu metallic glass, however, alloying with Co remarkably improves the hydrogenation kinetics and storage capacities. Apparent activation energies for hydrogenation are calculated to be 64.4 kJ/mol, and 107.2 kJ/mol, for the Mg60Ce10Ni20Cu5Co5 and Mg60Ce10Ni20Cu5Zn5 metallic glasses, respectively. Theoretical calculations are performed to understand the atomic structure of the five-component metallic glasses. It shows that the overall, Mg Mg pair and Mg Ni pair distribution functions (PDFs) of the Mg60Ce10Ni20Cu5Co5 and Mg60Ce10Ni20Cu5Zn5 metallic glasses are almost the same, indicating that geometry issue is not a key factor on influencing the hydrogenation properties of the studied Mg-based metallic glasses. It is proposed that chemical composition is the key to improve the hydrogenation properties of Mg-based metallic glasses.
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- 2019
13. Abnormal bonding ways in Zr50Cu50 metallic glass under high pressures
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Xin Ye, Ji Wang, Heng Kang, Shaopeng Pan, and Li-Min Wang
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Materials science ,Amorphous metal ,Mechanical Engineering ,Coordination number ,Metals and Alloys ,02 engineering and technology ,Pressure dependence ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Symmetry (physics) ,0104 chemical sciences ,Molecular dynamics ,Mechanics of Materials ,Chemical physics ,Atom ,Materials Chemistry ,0210 nano-technology - Abstract
The atomic structures of Zr50Cu50 metallic glasses (MGs) under high pressures from 0 GPa to 150 GPa are investigated via molecular dynamics simulations. We found that as pressure and density increase, local structural parameters such as coordination number, five-fold symmetry and quasi-nearest atom reach maxima (or minima) at 60 GPa, rather than monotonous pressure dependence. Atomic structure analyses uncover unexpected shortening of Zr-Zr bonding of Zr50Cu50 MGs under high pressures, responsible for the change of atomic packing in Zr50Cu50 MGs from dense to loose while pressure increasing. Furthermore, composition segregation is observed at high pressures, resulted from the new finding that the Zr-Zr and Cu-Cu bonding are much easier to decrease than Zr-Cu under high pressures. The results help to understand the behaviors of metallic glasses under extreme conditions.
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- 2019
14. The medium-range orders transition in liquid Fe–Al alloys
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Jin Wang, Jingyu Qin, Bangshao Dong, Shaopeng Pan, and Xinxin Li
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Materials science ,General Computer Science ,Magnetic moment ,Al content ,General Physics and Astronomy ,Thermodynamics ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Ab initio molecular dynamics ,Computational Mathematics ,Mechanics of Materials ,Medium range ,Atom ,General Materials Science ,0210 nano-technology - Abstract
We observed the transition of medium-range orders (MROs) and physical properties in liquid Fe–Al alloys by using ab initio molecular dynamics simulation. Above 66 at. % Al, only Fe–Fe MRO exists, while in other binary Fe–Al alloys studied Fe–Fe and Al–Al MROs coexist, and below 50 at. % Al, Al–Al MRO turns to be dominant. The curve of short-range order around Fe atoms versus Al content also shows a juncture at 66 at. % Al above which polyhedron type increase significantly, correspondingly a significant decrease of the average magnetic moment per Fe atom is observed. In addition, the self-diffusion coefficient of Al atom increases sharply above 66 at. % Al.
- Published
- 2019
15. Tailoring the corrosion behavior of Fe-based metallic glasses through inducing Nb-triggered netlike structure
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Ki Buem Kim, Shaopeng Pan, J. Pang, C.G. Jia, Yongang Zhang, Jiayang Qin, and Weimin Wang
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Materials science ,Amorphous metal ,Annealing (metallurgy) ,020209 energy ,General Chemical Engineering ,Potentiodynamic polarization ,02 engineering and technology ,General Chemistry ,021001 nanoscience & nanotechnology ,Amorphous solid ,Corrosion ,0202 electrical engineering, electronic engineering, information engineering ,General Materials Science ,Fe based ,Composite material ,0210 nano-technology ,Corrosion behavior ,Porosity - Abstract
The atomic structure and corrosion behavior of Fe87-xB13Nbx (x = 0, 7, 10 and 13) metallic glasses were investigated using various experimental techniques and simulations. The netlike (Fe, Nb)23B6 structure units, which took root in the Nb-contained amorphous matrix, emerged after annealing and raised markedly corrosion resistance of as-spun amorphous samples as cNb > 7 at.%, such as the occurrence of wider passive platform in the potentiodynamic polarization plots and the transformation from the porous holes to stable passive films on corrosion surfaces.
- Published
- 2019
16. Rejuvenation by weakening the medium range order in Zr46Cu46Al8 metallic glass with pressure preloading: A molecular dynamics simulation study
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Shaopeng Pan, Kang Cheung Chan, R.P. Liu, L. Qi, Shidong Feng, L. Zhao, and Li-Min Wang
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010302 applied physics ,Materials science ,Amorphous metal ,Mechanical Engineering ,Enthalpy ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Microstructure ,01 natural sciences ,Molecular dynamics ,Shear (geology) ,Mechanics of Materials ,0103 physical sciences ,lcsh:TA401-492 ,General Materials Science ,lcsh:Materials of engineering and construction. Mechanics of materials ,Composite material ,0210 nano-technology ,Elastic modulus ,Excitation ,Rejuvenation - Abstract
Rejuvenation is the structural excitation of metallic glasses that can significantly increase the enthalpy and free volume. Here, the rejuvenation in Zr46Cu46Al8 metallic glasses with pressure preloading was studied by molecular dynamics simulation. As the strain gradually increases, high-density deformation units in different regions are formed in the rejuvenated Zr46Cu46Al8 metallic glass with pressure preloading, but they do not form the shear bands that cause brittle fracture. In terms of the microstructure, the pressure preloading increases the degree of the short range order, but decreases the medium range order. 3-atom connections in the medium range order of icosahedra and other clusters are proposed to represent the level of rejuvenation. The decrease of 3-atom connections in the medium range order can lower the energy barrier and decrease the elastic modulus, improving the level of the rejuvenation. With the weakening of the 3-atom connections, the rejuvenated metallic glass possesses the features of high density, high energy, high Poisson's ratio, high defects and low localization. These findings open an avenue to evaluate the level of rejuvenation and provide a strong foundation for metallic glass design. Keywords: Metallic glass, Rejuvenation, Pressure, Plasticity, Molecular dynamic simulation
- Published
- 2018
17. Structural and bonding transformation of Al0.67CrCoCuFeNi high-entropy alloys during quenching
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Bingchen Wei, Shaopeng Pan, Yating Zhang, Kun Zhang, and Weiqi Tang
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010302 applied physics ,Quenching ,Materials science ,Mechanical Engineering ,High entropy alloys ,Metals and Alloys ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Transformation (music) ,Amorphous solid ,law.invention ,Molecular dynamics ,Cooling rate ,Mechanics of Materials ,Chemical physics ,law ,0103 physical sciences ,Materials Chemistry ,Intermediate state ,Crystallization ,0210 nano-technology - Abstract
Structural and bonding transformation of the Al0.67CrCoFeNi high-entropy alloys (HEA) during quenching is investigated by molecular dynamics simulations. At a high cooling rate, some short-ranged ordered clusters, such as FCC, HCP and BCC crystalline clusters are already present in the almost amorphous HEAs. When the cooling rate decreases, the atoms become packed more orderly and ultimately form a nano-polycrystalline structure dominated by FCC structures. The BCC structures appear only as an intermediate state acting on the course of crystallization, while the HCP structure can be viewed as the precursor of the malposed FCC structure due to the identical first neighbor distances. In liquid HEAs, the low-symmetry and low-coordination bond pairs, either transform to high-symmetry and high-coordination 1551 bond pairs, or transform to 1(5,4)41 bond pairs for FCC structure and 1661 bond pairs for an HCP structure, depending on the cooling rates. This study will contribute to a better understanding of the essential phase change in HEAs.
- Published
- 2018
18. Tailoring hydrogen storage properties of amorphous Mg 65 Cu 25 Y 10 alloy via minor alloying addition of Ag
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Huaijun Lin, Liqing He, Wei Li, Peng Zhang, Shaopeng Pan, and Zhiguo Zhang
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Materials science ,Hydrogen ,Hydride ,Mechanical Engineering ,Alloy ,Metals and Alloys ,chemistry.chemical_element ,02 engineering and technology ,General Chemistry ,engineering.material ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Amorphous solid ,Hydrogen storage ,chemistry ,Nanocrystal ,Chemical engineering ,Mechanics of Materials ,Materials Chemistry ,engineering ,Dehydrogenation ,0210 nano-technology - Abstract
Minor alloying addition of Ag improves the hydrogen storage capacity and reduces the dehydrogenation temperature of the amorphous Mg65Cu25Y10 alloy. Hydrogen storage capacity is increased from 2.1 wt% to 3.2 wt% when substituting Mg by only 1 at% of Ag. After hydrogenation, the amorphous Mg-Cu-Y(-Ag) alloys decompose into two types of sites for hydrogen occupations: i.e. a new amorphous Mg-Cu(-Ag) hydride clusters and YH3 nanocrystals. This study shows a simple method to tailor hydrogen storage properties of amorphous Mg65Cu25Y10 alloy.
- Published
- 2018
19. Large-sized quasi-crystals with continuously adjustable compositions
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Shaopeng Pan, Changzeng Fan, Zijing Li, Li-Min Wang, Jianbing Qiang, Linran Zhao, and Chuang Dong
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Range (particle radiation) ,Materials science ,Mechanical Engineering ,Alloy ,Metals and Alloys ,Quasicrystal ,chemistry.chemical_element ,02 engineering and technology ,Composition (combinatorics) ,engineering.material ,021001 nanoscience & nanotechnology ,01 natural sciences ,chemistry ,Mechanics of Materials ,0103 physical sciences ,Materials Chemistry ,engineering ,Maximum size ,Beryllium ,Composite material ,010306 general physics ,0210 nano-technology - Abstract
The quasi-crystal-forming alloys with adjustable compositions were prepared by element-addition to a pre-existing pure quasi-crystalline system. The protocol alloy Zr40Ti40Ni20 was chosen as the parent alloy, and beryllium was used as the additive element. The quasi-crystal forming ability was found to be enhanced with Be content within a wide composition range of (Zr40Ti40Ni20)100-xBex (0 ≤ x ≤ 16). A maximum size of up to 10 mm in diameter of pure quasi-crystalline rod was attained at a composition of (Zr40Ti40Ni20)84Be16. Structural analyses show that Be-addition continuously reduces the interplanar spacing. The mechanism of the enhanced quasi-crystal forming ability was also discussed.
- Published
- 2018
20. Anomalies in the dynamics of a metallic glass-forming liquid under super-high pressure
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Shaopeng Pan, Zijing Li, Li-Min Wang, Heng Kang, and Shidong Feng
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Amorphous metal ,Materials science ,Dynamics (mechanics) ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Local structure ,Atomic and Molecular Physics, and Optics ,Isothermal process ,0104 chemical sciences ,Electronic, Optical and Magnetic Materials ,Metal ,Mean squared displacement ,Molecular dynamics ,Chemical physics ,visual_art ,High pressure ,Materials Chemistry ,visual_art.visual_art_medium ,Physical and Theoretical Chemistry ,0210 nano-technology ,Spectroscopy - Abstract
The atomic dynamics of a Zr50Cu50 metallic glass-forming liquid has been investigated in isothermal compression by using molecular dynamics simulations. It is found that the mean square displacement (MSD) for Zr is unexpectedly larger than that for Cu under super-high pressures. This interesting result challenges our understanding that the Cu atoms are always faster than Zr atoms in normal liquids, suggesting that the atomic dynamics for Zr becomes extraordinary under super-high pressure. We found that the shorter-bonded Zr atoms can be formed under-super high pressure because of the remarkable softness of Zr-Zr bonding ways. Further studies suggest that this special local structure is responsible for the unexpected atomic dynamics of Zr. These results shed light on the understanding of the inimitable dynamics in Zr-based metallic glass-forming liquids under super-high pressure.
- Published
- 2021
21. Mg fragments and Al bonded networks in liquid Mg–Al alloys
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Jin Wang, Shaopeng Pan, Xinxin Li, and Jingyu Qin
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Materials science ,General Computer Science ,Diffusion ,Ab initio ,General Physics and Astronomy ,02 engineering and technology ,General Chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Structural evolution ,Complex metallic alloys ,Lower energy ,Ab initio molecular dynamics ,Computational Mathematics ,Crystallography ,Mechanics of Materials ,Pair correlation ,0103 physical sciences ,General Materials Science ,Structured model ,010306 general physics ,0210 nano-technology - Abstract
The structural evolution of liquid Mg–Al alloys has been investigated with composition variation from pure Mg to Al at 973 K using ab initio molecular dynamics simulation. The local structures are characterized in terms of pair correlation functions, coordinate numbers, and bond pairs. The atomic interactions are evaluated by the electronic structures to reveal the formation mechanism of the liquid structures. As a result of the fact that the formation of Mg–Al bonds is actually restrained by Al–Al bonds with lower energy, the initial local structures around Mg trend to be maintained as the fragments during the structural evolution, and the discrete Al atoms transforms to be segregated around Mg in the composition region from 18.75 to 31.25 at.% Al. Based on these structural characteristics, the liquid structures are modeled as the Al bonded networks surrounding Mg fragments. Further, the dynamical properties are reflected by the self-diffusion coefficients. The results show that the diffusion of Mg atoms is actually limited by Al bonded networks, which confirm the reliability of the model. It is also worth expecting that the structure model may provide a new viewpoint for further study on the complex metallic alloys in solid Mg–Al system.
- Published
- 2017
22. Correlation between initial structure and athermal quasi-static compressive deformation in a metallic glass
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Xiaofeng Niu, Shaopeng Pan, Junwei Qiao, Shidong Feng, Weimmin Wang, and Jingyu Qin
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Materials science ,Amorphous metal ,Strain (chemistry) ,Condensed matter physics ,Mechanical Engineering ,Metals and Alloys ,Heterojunction ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Displacement (vector) ,Molecular dynamics ,Crystallography ,Mechanics of Materials ,0103 physical sciences ,Atom ,Materials Chemistry ,Deformation (engineering) ,010306 general physics ,0210 nano-technology ,Quasistatic process - Abstract
Athermal quasi-static compressive deformation for a model metallic glass is investigated by molecular dynamics simulations. A new structural parameter, quasi-nearest atom (QNA), is used to characterize local atomic packing of initial structure. We find that regions with higher nonaffine displacement have more atoms with more QNA. The coarse grained number of QNAs exhibits significant spatial heterogeneities and these structural fluctuations show close correlation with the nonaffine displacement. The correlation between the coarse grained number of QNA and nonaffine displacement does not decrease as the strain increases but show the maximum at a certain strain, indicating that strain localized regions are activated individually. Therefore, our results provide a direct evidence of the correlation between atomic structure and deformation in metallic glass.
- Published
- 2017
23. Enhanced nucleation and refinement of eutectic Si by high number-density nano-particles in Al–10Si–0.5Sb alloys
- Author
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Zhonghai Zhou, Fengxiang Guo, Xuelei Tian, Wenhui Yu, Shaopeng Pan, Dan Liu, Yong Zhang, Jingyu Qin, Wang Wei, and Wang Yao
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010302 applied physics ,Materials science ,Chemical substance ,Number density ,Mechanical Engineering ,Alloy ,Nucleation ,Nanoparticle ,02 engineering and technology ,engineering.material ,021001 nanoscience & nanotechnology ,01 natural sciences ,Crystallography ,Mechanics of Materials ,0103 physical sciences ,Eutectic bonding ,engineering ,lcsh:TA401-492 ,General Materials Science ,Lamellar structure ,lcsh:Materials of engineering and construction. Mechanics of materials ,0210 nano-technology ,Eutectic system - Abstract
The mechanism of refinement of eutectic Si with Sb additions in an Al–10 wt.% Si alloy is studied. The increased holding time designates a transition of the eutectic nucleation temperature from a decreased value to an increased one, accompanied by a morphological transformation of eutectic Si from lamellar to a shorter, rod-like shape. By ab initio molecular dynamics simulation, the chemical short-range order of −0.002 demonstrates weak affinity in the Al–Sb pair, which does not favor the existence of AlSb clusters in the melts. Sb–Sb segregation and the Sb–Si repulsive force are revealed, which promote the formation of Al-enriched precursors and the accumulation of Si atoms adjacent to precursors, inducing precursor nucleation. Continuous attachment of precursors and individual Si atoms during Si growth results in the high number-density nano-particles and suppresses the formation of twin grains within eutectic Si. Keywords: Al–Si alloys, High number-density nano-particle, Precursor-assisted nucleation, Atomic structure, Eutectic Si refinement
- Published
- 2017
24. Effect of Al on the atomic structure in Zr50Cu40Al10 metallic glass
- Author
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Shaopeng Pan, Aidong Lan, Xiaochao Zhang, and Junwei Qiao
- Subjects
010302 applied physics ,education.field_of_study ,Amorphous metal ,Ternary numeral system ,Materials science ,General Computer Science ,Icosahedral symmetry ,Kinetics ,Population ,General Physics and Astronomy ,02 engineering and technology ,General Chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Computational Mathematics ,Crystallography ,Molecular dynamics ,Mechanics of Materials ,Chemical physics ,Medium range ,0103 physical sciences ,Short range order ,General Materials Science ,0210 nano-technology ,education - Abstract
The icosahedral short-range order and medium-range order of Zr50Cu50 and Zr50Cu40Al10 metallic glasses have been investigated by molecular dynamics simulations. Our analysis shows that, although the replacement of a few percent of Cu by Al enlarges the population of full icosahedra (FIs), the degree of interpenetrating aggregation for FIs is reduced which might be caused by the strong avoidance of Al-centered FIs in the ternary system. However, this fact does not mean the weakness of icosahedral medium range order in Zr50Cu40Al10 metallic glass. If the interpenetrating and non-interpenetrating connections are both considered, the largest super-cluster formed by the connected FIs in Zr50Cu40Al10 is rather larger than that in Zr50Cu50, which might play an important role in slowing down the kinetics and thus enlarge the glass-forming ability.
- Published
- 2017
25. Towards easily tunable hydrogen storage via a hydrogen-induced glass-to-glass transition in Mg-based metallic glasses
- Author
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Dong Peng Wang, Min He, Tian Pei Ge, Jiangwen Liu, Huaijun Lin, Weihua Wang, L.Z. Ouyang, Lin Gu, Shaopeng Pan, Min Zhu, Hai Wen Li, Etsuo Akiba, and Hui Wang
- Subjects
Materials science ,Amorphous metal ,Polymers and Plastics ,Hydrogen ,Metals and Alloys ,chemistry.chemical_element ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Enthalpy of mixing ,01 natural sciences ,0104 chemical sciences ,Electronic, Optical and Magnetic Materials ,Hydrogen storage ,Chemical engineering ,chemistry ,Hydrogen fuel ,Scanning transmission electron microscopy ,Ceramics and Composites ,Dehydrogenation ,0210 nano-technology ,Glass transition - Abstract
The exploration of favourable hydrogen storage materials is of great importance for the realization of a sustainable hydrogen energy society. Here, we report a hydrogen-induced glass-to-glass transition in Mg-based metallic glasses (MGs) with a storage capacity as high as 5 wt%-H. The hydrogen storage capacity of metallic glassy hydrides (MGHs) is obviously higher than that of their crystalline counterparts owing to the free volume and disordered atomic structure associated with glasses. The glass-to-glass transition is demonstrated by direct experimental observation using aberration-corrected scanning transmission electron microscopy combined with ab initio molecular dynamics simulations. Remarkably, the dehydrogenation temperature of the MGHs can be efficiently tuned as it shows a close relationship with the enthalpy of mixing between the alloying element and hydrogen, and can be decreased from ∼350 °C to ∼150 °C when alloying with 5 at.%-Cu. MGs therefore have great potential as solid-state hydrogen storage materials.
- Published
- 2016
26. Correlation between local structure and dynamic heterogeneity in a metallic glass-forming liquid
- Author
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Shidong Feng, Weimin Wang, Shaopeng Pan, Jingyu Qin, and Junwei Qiao
- Subjects
Materials science ,Amorphous metal ,Mechanical Engineering ,Metals and Alloys ,Atomic mobility ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Spatial distribution ,01 natural sciences ,Potential energy ,Local structure ,Condensed Matter::Soft Condensed Matter ,Molecular dynamics ,Mechanics of Materials ,Chemical physics ,0103 physical sciences ,Materials Chemistry ,Dynamical heterogeneity ,010306 general physics ,0210 nano-technology ,Supercooling - Abstract
Dynamic heterogeneity as one of the most important properties in supercooled liquids has been found for several decades. However, its structural origin remains open for many systems. Here, we propose a new structural parameter to characterize local atomic packing in metallic liquids. It is found that the new parameter in a simulated metallic glass-forming liquid is closely correlated with potential energy and atomic mobility. It also exhibits significant spatial heterogeneities and these structural fluctuations show close correlation with the spatial distribution of the long-time dynamic propensities. Therefore, our results provide a direct evidence of the correlation between atomic structure and dynamical heterogeneity. The new structural parameter might be used to reflect the structural “defect” in metallic liquids and glasses and further play an important role to uncover the structure-property relationship in these disordered systems.
- Published
- 2016
27. Effects of flow defects on hypothetical ZrCu metallic glasses microstructure and plasticity: A molecular dynamics analysis
- Author
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Guoliang Li, Shidong Feng, X.Y. Zhang, Shaopeng Pan, R.P. Liu, L. Qi, Suhong Zhang, Mingzhen Ma, and Na Xu
- Subjects
Microstructural evolution ,Materials science ,Amorphous metal ,Mechanical Engineering ,Flow (psychology) ,Metals and Alloys ,Plasticity ,Microstructure ,Molecular dynamics ,Mechanics of Materials ,Materials Chemistry ,Forensic engineering ,Composite material ,Mechanical instability - Abstract
The effects of flow defects of hypothetical metallic glasses on the microstructure and plasticity are investigated through the use of a molecular dynamics simulation. With the design concept of increasing plasticity, the hypothetical metallic glass containing much effective flow defects is successfully simulated by using Zr45Cu45Al10 metallic glass as the precursor. Simulation reproduces the images depicting the microstructural evolution after yielding the required flow defects. This model analysis quantitatively demonstrates that the yielding flow defects render hypothetical metallic glasses closer to their liquid structure. The flow defects lead to only small reductions in strength, but to a significantly enhanced plasticity. The simulation results are in good agreement with those obtained by experiment. These findings provide physical insight into the mechanical instability and provide a strong foundation for future metallic glass designs.
- Published
- 2016
28. The atomic structure of liquid Fe–C alloys
- Author
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Shaopeng Pan, Bangshao Dong, Junwei Qiao, Shidong Feng, and Jingyu Qin
- Subjects
Materials science ,Mechanical Engineering ,Metals and Alloys ,Ab initio ,Composition (combinatorics) ,Polyhedron ,Crystallography ,Antiprism ,Mechanics of Materials ,Materials Chemistry ,Voronoi diagram ,Intensity (heat transfer) ,Eutectic system ,Phase diagram - Abstract
The structures of liquid Fe–C alloys in the Fe-rich end were investigated by ab initio molecular dynamics simulations. The trend of intensity of chemical short range order around Fe and C atoms changes at the eutectic composition, indicating the close correlation between liquid structure and phase diagram. The tri-capped trigonal prism (Voronoi index ) and mono-capped square archimedean antiprism (Voronoi index ) around C atoms have the largest frequency fractions and the longest lifetimes among all the polyhedra. Moreover, they tend to connect with each other to form network structure. The maximum intensity of network structure is located at the 20% C composition, which might be the reason why alloys near eutectic composition have great glass-forming ability.
- Published
- 2015
29. Effect of Y on the structure-property relationship of Mg65Cu25Y10 metallic glass
- Author
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Shidong Feng, Shaopeng Pan, Xiaofeng Niu, Junwei Qiao, and Guoxin Yao
- Subjects
Materials science ,Amorphous metal ,General Computer Science ,General Physics and Astronomy ,Structure property ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Glass forming ,Symmetry (physics) ,0104 chemical sciences ,Computational Mathematics ,Molecular dynamics ,Polyhedron ,Chemical bond ,Mechanics of Materials ,Chemical physics ,General Materials Science ,0210 nano-technology - Abstract
The effect of Y minor addition on the structure-property relationship of Mg65Cu25Y10 metallic glass was investigated through molecular dynamics simulations. The average local five-fold symmetry is reduced and the number of quasi-nearest atoms increases in Mg65Cu25Y10, indicating a lower atomic packing. This fact is inconsistent to the normal effect of minor elements to enhance the glass-forming ability by enlarging the atomic packing of the systems. Although the reduce of atomic packing, the numbers of icosahedra and some other Kasper polyhedra with the fewest disclinations increase in Mg65Cu25Y10. That might be the reason for the larger glass forming ability of Mg65Cu25Y10 than Mg65Cu35. Moreover, the strength of Mg65Cu25Y10 is not weakened by the low atomic packing, which might result from the strong chemical bonding of Cu-Y. Our results are helpful to understand the effect of minor elements on the properties of metallic glasses.
- Published
- 2020
30. Structural controllability of general edge dynamics in complex network
- Author
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Shaopeng Pang, Yue Zhou, Xiang Ren, and Fangzhou Xu
- Subjects
Medicine ,Science - Abstract
Abstract Dynamic processes that occur on the edge of complex networks are relevant to a variety of real-world systems, where states are defined on individual edges, and nodes are active components with information processing capabilities. In traditional studies of edge controllability, all adjacent edge states are assumed to be coupled. In this paper, we release this all-to-all coupling restriction and propose a general edge dynamics model. We give a theoretical framework to study the structural controllability of the general edge dynamics and find that the set of driver nodes for edge controllability is unique and determined by the local information of nodes. Applying our framework to a large number of model and real networks, we find that there exist lower and upper bounds of edge controllability, which are determined by the coupling density, where the coupling density is the proportion of adjacent edge states that are coupled. Then we investigate the proportion of effective coupling in edge controllability and find that homogeneous and relatively sparse networks have a higher proportion, and that the proportion is mainly determined by degree distribution. Finally, we analyze the role of edges in edge controllability and find that it is largely encoded by the coupling density and degree distribution, and are influenced by in- and out-degree correlation.
- Published
- 2023
- Full Text
- View/download PDF
31. Atomic structure of shear bands in Cu64Zr36 metallic glasses studied by molecular dynamics simulations
- Author
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L. Qi, Xinyu Zhang, Shaopeng Pan, Gong Li, Shidong Feng, Riping Liu, Mingzhen Ma, and Li-Min Wang
- Subjects
Shear (sheet metal) ,Molecular dynamics ,Matrix (mathematics) ,Amorphous metal ,Fractal ,Materials science ,Polymers and Plastics ,Computational chemistry ,Metals and Alloys ,Ceramics and Composites ,Molecular physics ,Mechanical instability ,Electronic, Optical and Magnetic Materials - Abstract
Molecular dynamics simulations on the atomic structure of shear bands (SBs) in Cu64Zr36 metallic glasses are presented. Results show that the atoms in the SB move desultorily, in contrast to those in the matrix. The saturated degree of bonded pairs considering the “liquid-like” character of SB quantitatively provides important details in extending earlier studies on SBs. Zr-centered 〈0, 2, 8, 5〉 clusters exhibit strong spatial correlations and tendency to connect with each other in short-range order. The 〈0, 2, 8, 5〉 cluster-type medium-range order is the main feature inside the SB relative to the matrix. The fractal results demonstrate the planar-like fashion of the 〈0, 2, 8, 5〉 network in SB, forming an interpenetrating solid-like backbone. Such heterogeneous structure provides a fundamental structural perspective of mechanical instability in SB.
- Published
- 2015
32. Structural origin of fractional Stokes-Einstein relation in glass-forming liquids
- Author
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Shaopeng Pan, Maozhi Li, Limei Xu, Z. W. Wu, and W. H. Wang
- Subjects
Physics ,Multidisciplinary ,Condensed matter physics ,Network structure ,Statistics::Other Statistics ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Condensed Matter::Disordered Systems and Neural Networks ,01 natural sciences ,Article ,Glass forming ,Molecular dynamics ,Percolation theory ,Percolation ,Stokes einstein ,0103 physical sciences ,Cluster (physics) ,Physics::Chemical Physics ,010306 general physics ,0210 nano-technology ,Glass transition - Abstract
In many glass-forming liquids, fractional Stokes-Einstein relation (SER) is observed above the glass transition temperature. However, the origin of such phenomenon remains elusive. Using molecular dynamics simulations, we investigate the break- down of SER and the onset of fractional SER in a model of metallic glass-forming liquid. We find that SER breaks down when the size of the largest cluster consisting of trapped atoms starts to increase sharply at which the largest cluster spans half of the simulations box along one direction, and the fractional SER starts to follows when the largest cluster percolates the entire system and forms 3-dimentional network structures. Further analysis based on the percolation theory also confirms that percolation occurs at the onset of the fractional SER. Our results directly link the breakdown of the SER with structure inhomogeneity and onset of the fraction SER with percolation of largest clusters, thus provide a possible picture for the break- down of SER and onset of fractional SER in glass-forming liquids, which is is important for the understanding of the dynamic properties in glass-forming liquids.
- Published
- 2017
33. Structural evolution of nanoscale metallic glasses during high-pressure torsion: A molecular dynamics analysis
- Author
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R.P. Liu, Guoliang Li, W. Jiao, Shidong Feng, Shaopeng Pan, Mingzhen Ma, L. Qi, W. H. Wang, and Jing Qin
- Subjects
010302 applied physics ,Multidisciplinary ,Amorphous metal ,Materials science ,Condensed matter physics ,Torsion (mechanics) ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Structural evolution ,Article ,Molecular dynamics ,Homogeneous ,High pressure ,0103 physical sciences ,Shear matrix ,0210 nano-technology ,Nanoscopic scale - Abstract
Structural evolution in nanoscale Cu50Zr50 metallic glasses during high-pressure torsion is investigated using molecular dynamics simulations. Results show that the strong cooperation of shear transformations can be realized by high-pressure torsion in nanoscale Cu50Zr50 metallic glasses at room temperature. It is further shown that high-pressure torsion could prompt atoms to possess lower five-fold symmetries and higher potential energies, making them more likely to participate in shear transformations. Meanwhile, a higher torsion period leads to a greater degree of forced cooperative flow. And the pronounced forced cooperative flow at room temperature under high-pressure torsion permits the study of the shear transformation, its activation and characteristics, and its relationship to the deformations behaviors. This research not only provides an important platform for probing the atomic-level understanding of the fundamental mechanisms of high-pressure torsion in metallic glasses, but also leads to higher stresses and homogeneous flow near lower temperatures which is impossible previously.
- Published
- 2016
- Full Text
- View/download PDF
34. Tuning deformation behavior of Cu0.5CoNiCrAl high-entropy alloy via cooling rate gradient: An atomistic study
- Author
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Riping Liu, Kang Cheung Chan, Shaopeng Pan, Lin Li, Shidong Feng, L. Zhao, and Li-Min Wang
- Subjects
010302 applied physics ,Materials science ,Strain (chemistry) ,Mechanical Engineering ,Alloy ,technology, industry, and agriculture ,Metals and Alloys ,Nucleation ,02 engineering and technology ,General Chemistry ,engineering.material ,021001 nanoscience & nanotechnology ,01 natural sciences ,Structural heterogeneity ,Condensed Matter::Materials Science ,Molecular dynamics ,Cooling rate ,Mechanics of Materials ,Chemical physics ,0103 physical sciences ,Materials Chemistry ,engineering ,Deformation (engineering) ,Dislocation ,0210 nano-technology - Abstract
The deformation behaviors of body-centered cubic Cu 0.5 CoNiCrAl high-entropy alloys processed by the cooling rate gradient are investigated by the molecular dynamics simulations. The plastic deformation ability of the high-entropy alloy is significantly improved by triggering multiple-type dislocation slips along different deformation paths. The cooling rate gradient introduces abundant atomic vacancies, proliferating the nucleation sites of dislocations. Additionally, the nucleation barriers of dislocations are reduced by the resultant structural disorder, high potential energy and chemical segregation. Consequently, the cooling rate gradient enhances the structural heterogeneity, promoting the formation of multiple deformation paths and preventing strain localization.
- Published
- 2019
35. Insight into thermodynamics and corrosion behavior of Al–Ni–Gd glassy alloys from atomic structure
- Author
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Jingyu Qin, Zhonghua Zhang, G.H. Li, Weimin Wang, and Shaopeng Pan
- Subjects
Materials science ,General Chemical Engineering ,Alloy ,Ab initio ,Thermodynamics ,General Chemistry ,engineering.material ,Electrochemistry ,Corrosion ,Molecular dynamics ,Metastability ,Pitting corrosion ,engineering ,General Materials Science ,Polarization (electrochemistry) - Abstract
To clarify the relation between the thermodynamics and metastable pitting behavior of Al–Ni–Gd glassy alloys, the as-spun ribbons were investigated using various experimental methods and ab initio molecular dynamic simulations. The results show that the relative area of main peak shoulder in XRD patterns, onset crystallization temperature, contraction degree of samples increase with increasing c Ni . The peak for the metastable pitting events in the polarization curves with Cl − containing solutions is accelerated by increasing c Ni . The variation of thermal and electrochemical properties of samples is attributed to the strong interaction of Al–Ni bond based on the atomic structure analysis.
- Published
- 2013
36. Structural disorder in metallic glass-forming liquids
- Author
-
Shidong Feng, Bangshao Dong, Shaopeng Pan, Junwei Qiao, Jingyu Qin, Xiaofeng Niu, Weimin Wang, and Li-Min Wang
- Subjects
Multidisciplinary ,Amorphous metal ,Materials science ,Relaxation (NMR) ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Potential energy ,Article ,Metal ,Molecular dynamics ,Chemical physics ,visual_art ,0103 physical sciences ,Atom ,visual_art.visual_art_medium ,010306 general physics ,0210 nano-technology - Abstract
We investigated structural disorder by a new structural parameter, quasi-nearest atom (QNA), in atomistic configurations of eight metallic glass-forming systems generated through molecular dynamics simulations at various temperatures. Structural analysis reveals that the scaled distribution of the number of QNA appears to be an universal property of metallic liquids and the spatial distribution of the number of QNA displays to be clearly heterogeneous. Furthermore, the new parameter can be directly correlated with potential energy and structural relaxation at the atomic level. Some straightforward relationships between QNA and other properties (per-atom potential energy and α-relaxation time) are introduced to reflect structure-property relationship in metallic liquids. We believe that the new structural parameter can well reflect structure disorder in metallic liquids and play an important role in understanding various properties in metallic liquids.
- Published
- 2016
37. The formation of FeZn13 phase from atomic cluster during hot dip galvanizing
- Author
-
Xuezheng Li, Haozhi Yang, Jingyu Qin, Shaopeng Pan, and Bangshao Dong
- Subjects
Diffraction ,General Computer Science ,Alloy ,Ab initio ,General Physics and Astronomy ,chemistry.chemical_element ,General Chemistry ,Zinc ,engineering.material ,Radial distribution function ,Computational Mathematics ,Crystallography ,Molecular dynamics ,chemistry ,Mechanics of Materials ,Chemical physics ,Phase (matter) ,Physics::Atomic and Molecular Clusters ,engineering ,General Materials Science ,Voronoi diagram - Abstract
The liquid structure of Zn95Fe5 alloy was studied by ab initio molecular dynamic simulations. The important variation tendency of pair correlation function has been characterized. It is found that the interaction of unlike atoms is stronger than the like atoms. Voronoi polyhedron analysis reveals that icosahedral-like clusters are frequently found around Fe and the dominated voronoi polyhedrons around Zn atoms are icosahedral-like and deformed-bcc clusters. Chemical short range order analysis suggests that there are 12 Zn atoms around Fe, which is similar to the structure of FeZn13 phase. More importantly, this simulated result is proved indirectly by the experiment that a mass of FeZn13 phase was confirmed in zinc slag by X-ray diffraction, which indicates that the liquid structure is partially kept during solidification process.
- Published
- 2012
38. Crystallization pathways of liquid-bcc transition for a model iron by fast quenching
- Author
-
Weimin Wang, Shaopeng Pan, Shidong Feng, Junwei Qiao, and Jingyu Qin
- Subjects
Quenching ,Multidisciplinary ,Computer science ,Icosahedral symmetry ,Coordination number ,Data science ,Potential energy ,Article ,law.invention ,Crystal ,Local symmetry ,law ,Chemical physics ,Phase (matter) ,Crystallization - Abstract
We report simulations on the local structural evolution in the liquid-bcc transition of a model iron. Fourteen main Voronoi polyhedra are chosen as the representatives of short-range orders (SROs) and their transformations during crystallization are also investigated. Thus, the crystallization pathways for the main SROs are drawn. Our results also show that the transformations between two SROs in the crystallization pathways can be classified into two categories, first the enlargement of coordination number, second the transformation of local symmetry from five-fold to four-fold. The former reduces the potential energy while the latter increases it. It is found that the potential energy cannot decease monotonously whatever crystallization pathway is chosen to transform the icosahedral SRO to bcc SRO. Therefore, the latter transformation might provide the energy barrier of crystallization. We propose two transformation styles among SROs. All the transformations in the crystallization pathways can be achieved according to the styles. Moreover, the two transformation styles indicates that the bcc structure is more similar to liquid than other crystals. That might be the reason why the first phase nucleated during a rapid cooling process should be bcc crystal.
- Published
- 2015
39. The Role of Individual Edges in Edge Controllability of Complex Networks
- Author
-
Chao Li and Shaopeng Pang
- Subjects
Complex networks ,edge dynamics ,controllability ,driven edges ,multimodality ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 - Abstract
Dynamical processes occurring on edges of complex networks are relevant to many real situations. Controlling the edge dynamics is a fundamental challenge in network science. Inspired by recent advances in the edge controllability theories, we explore the role of individual edges in the edge controllability by classifying each edge into one of three categories: critical, redundant, and intermittent. An analytical framework is developed to identify the category of each edge, leading to the discovery that the proportions of three types of edges are to a great extent encoded by the degree distribution, and are affected by the in- and out-degree correlation. In addition, we propose the probability distribution of intermittent edges, and find that the probability distribution has multimodality, which is common in model and real networks.
- Published
- 2020
- Full Text
- View/download PDF
40. Optimization of Wind Farm Self-Discipline Interval and Energy Storage System Configuration
- Author
-
Xiaodong Yu, Wen Zhang, Xiao Dong, Shulin Liu, Shaopeng Pang, and Hongzhi Zang
- Subjects
Wind power ,self-discipline ,energy storage system (ESS) ,optimization ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 - Abstract
The uncertain and stochastic output of the wind farm results in a lot of problems when it is connected to the power grid. In order to improve the wind power's friendship to the grid, the wind farm should has a certain self-discipline level. In this paper, it is studied from the perspective of the wind farm self-discipline interval. First, the concept of wind farm self-discipline interval is proposed, followed by a comprehensive index which is used to evaluate the wind farm self-discipline level by comprehensively considering the interval width and the interval accuracy. Second, an optimization method is discussed to obtain the optimal self-discipline interval. This method has general applicability, not only suitable for normal distribution and other known distributions but also for arbitrary distributions (such as non-symmetric, multi-peak distributions). Finally, the size of the energy storage system (ESS) in the wind farm is optimized to guarantee a suitable wind farm self-discipline level. Simulation results show that the proposed method not only effectively improves the self-discipline level of the wind farm but also has general applicability.
- Published
- 2020
- Full Text
- View/download PDF
41. A Data-Driven Based Framework of Model Optimization and Neural Network Modeling for Microbial Fuel Cells
- Author
-
Fengying Ma, Yankai Yin, Shaopeng Pang, Jiaxun Liu, and Wei Chen
- Subjects
Microbial fuel cells ,model optimization ,variable selection ,neural networks ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 - Abstract
Microbial fuel cells (MFCs) are devices that transform organic matters in wastewater into green energy. Microbial fuel cells systems have strong nonlinearity and high coupling, which involves control science, microbiology, electrochemistry and other disciplines. According to the requirements of microbial fuel cell system for model robustness and accuracy, we designed a comprehensive model optimization framework. Firstly, the influence of uncertain parameters on system was analyzed by combining global sensitivity analysis with uncertainty analysis. In accordance with analysis results, the uncertain parameters were optimized. Secondly, based on the optimized stochastic model, a simplified model was proposed by combining variable selection with neural networks. The results shown that the proposed framework can deeply analysis the influence of uncertain parameters on output, and provide theoretical basis for experimental research. It fully simplifies the original MFCs model, and has guiding significance for other types of fuel cells.
- Published
- 2019
- Full Text
- View/download PDF
42. The influence of clusters in the melt of Fe80Si10B10 alloy on the subsequent glass-formation
- Author
-
Zhengbang Li, Jingyu Qin, Bangshao Dong, Shaoxiong Zhou, and Shaopeng Pan
- Subjects
Amorphous metal ,Materials science ,Metallurgy ,Alloy ,Ab initio ,engineering.material ,Clusters ,Liquid structure ,Molecular dynamics ,Chemical engineering ,engineering ,General Materials Science ,General ,Metallic glasses ,Alloy melt ,Solid solution ,Glass-forming ability - Abstract
The structure of Fe 80 Si 10 B 10 alloy melt was investigated by ab initio molecular dynamic simulation from the local atomic environments. It presents that Fe 80 Si 10 B 10 alloy can be considered as the combination of B-centered prism-like clusters and bcc-like Fe-Si solid solution. The poor glass-forming ability of the alloy has been investigated and can be attributed to the bcc-like environment around Si atoms and the relative high content of pure Fe clusters.
- Full Text
- View/download PDF
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