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学者姓名：沙振东
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Abstract ：
Tailoring heterogeneities in amorphous alloys is a promising strategy for promoting the strength-ductility synergy. Here, molecular dynamics simulations are performed to investigate the effects of grains size and heterogeneous chemical composition on the mechanical properties of Mg-Cu nanoglasses (NGs). The reduced grain size in single-phase NGs improves the plasticity but at the expense of strength. In addition, the mechanical properties of dual-phase NGs composed of two chemical compositions depend critically upon the fraction of softer phase. In particular, the plasticity is improved for the low fraction of the softer phase, but is deteriorated for the high fraction of the softer phase, which is in striking contrast to the observations of the plasticity improvement reported in the traditional nanostructured metals/alloys. This is because that heterogeneities at the glass-glass interfaces intentionally introduce more stress concentration sites which are easier to accelerate the shear band formation. For an appropriate fraction of heterogeneous composition, a balance among strength and plasticity can be realized, which is useful for the design of novel NGs with high strength and superior ductility.
Keyword ：
glass-glass interface heterogeous nanocomposite mechanical property molecular dynamics nanoglass
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| GB/T 7714 | Chen, Yu , Ding, Jun , Sha, Zhen-Dong . Grain Size and Heterophase Effects on Mechanical Properties of Mg-Cu Nanoglasses [J]. | FRONTIERS IN MATERIALS , 2022 , 9 . |
| MLA | Chen, Yu 等. "Grain Size and Heterophase Effects on Mechanical Properties of Mg-Cu Nanoglasses" . | FRONTIERS IN MATERIALS 9 (2022) . |
| APA | Chen, Yu , Ding, Jun , Sha, Zhen-Dong . Grain Size and Heterophase Effects on Mechanical Properties of Mg-Cu Nanoglasses . | FRONTIERS IN MATERIALS , 2022 , 9 . |
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Abstract ：
In the present research work, the 2.25Cr1Mo0.25V steel plates with a thickness of 112 mm were welded using the multi-pass submerged automatic arc welding process. The creep specimens were prepared from the base metal (BM) and weld metal (WM) in the welded joint after heat treatment process. The uniaxial creep tests were performed to investigate the creep deformation and rupture behaviors at 550 degrees C under different applied stress levels. The microstructure and fracture surface morphology of crept BM and WM samples were also characterized using the scanning electron microscope with energy-dispersive X-ray spectroscopy. The results showed that typical three-stage creep deformation curves are observed in both BM and WM specimens, and the BM exhibits a faster deformation rate than the WM. Both the creep rupture time and uniaxial creep ductility are found to be increased with a decrease in applied stress. Furthermore, the relationship between the minimum creep rate and time to rupture of both BM and WM samples was obtained, and it can be described using a unified Monkman-Grant equation. In addition, it is found that the creep fractures of the BM and WM are a transgranular ductile failure. The creep damages of both materials are mainly associated with the microstructural degradations, that is, the initiation and coalescence of creep cavities at second phase particles such as carbide and inclusion particles along the loading direction.
Keyword ：
2 25Cr1Mo0 25V creep creep cavities life prediction weld
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| GB/T 7714 | Song, Yan , Chai, Mengyu , Lv, Junnan et al. Creep rupture behavior of 2.25Cr1Mo0.25V steel and weld for hydrogenation reactors under different stress levels [J]. | REVIEWS ON ADVANCED MATERIALS SCIENCE , 2022 , 61 (1) : 334-349 . |
| MLA | Song, Yan et al. "Creep rupture behavior of 2.25Cr1Mo0.25V steel and weld for hydrogenation reactors under different stress levels" . | REVIEWS ON ADVANCED MATERIALS SCIENCE 61 . 1 (2022) : 334-349 . |
| APA | Song, Yan , Chai, Mengyu , Lv, Junnan , Han, Zelin , Liu, Pan , Yan, Haoqi et al. Creep rupture behavior of 2.25Cr1Mo0.25V steel and weld for hydrogenation reactors under different stress levels . | REVIEWS ON ADVANCED MATERIALS SCIENCE , 2022 , 61 (1) , 334-349 . |
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Abstract ：
The sample size effect on the deformation behavior of metallic glasses (MGs) has recently become research of intense interest. An inverse sample size effect is observed in previous experimental studies; where the yield strength decreases with decreasing sample size, rather than increasing. We propose a theoretical analysis based on the shear banding process to rationalize the inherent size dependence of yield strength, showing an excellent agreement with experimental results. Our model reveals that the anomalous inverse size effect is, in fact, caused by a transition in failure mode; from a rapid shear banding process with a shear band (SB) traversing the entire sample in bulk MGs, to an immature shear banding process with propagated SBs only at the surface in micron-sized MGs. Our results fill the gap in the current understanding of size effects in the strength and failure mechanism of MGs at different length scales.
Keyword ：
failure mechanism metallic glass micropillar shear band size dependence yield strength
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| GB/T 7714 | Teng, Yun , Sha, Zhen-Dong . Uncovering the Inherent Size Dependence of Yield Strength and Failure Mechanism in Micron-Sized Metallic Glass [J]. | MATERIALS , 2022 , 15 (18) . |
| MLA | Teng, Yun et al. "Uncovering the Inherent Size Dependence of Yield Strength and Failure Mechanism in Micron-Sized Metallic Glass" . | MATERIALS 15 . 18 (2022) . |
| APA | Teng, Yun , Sha, Zhen-Dong . Uncovering the Inherent Size Dependence of Yield Strength and Failure Mechanism in Micron-Sized Metallic Glass . | MATERIALS , 2022 , 15 (18) . |
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Abstract ：
Despite that the pressure-promoted thermal rejuvenation is a promising remedy for the plasticity enhancement of metallic glasses (MGs), there has been so far little studies of the effect of rejuvenation on the fracture toughness of MGs. Herein, molecular dynamic simulations are performed to study the influence of annealing pressure (Pa) on the fracture energy (G) of rejuvenated MGs. Our results manifest that the G increases at first and then decreases with Pa, showing a two-stage behavior. The increase of G is attributed to the improved plasticity but marginal change of strength, while the decrease of G is caused by the significant reduction of strength. Another key finding is that the improved plasticity arises from the more homogeneous activation of shear transformation zones due to its lower activation energy in the high-energy rejuvenated state. The present study establishes the influence of Pa on G based on the internal structure analyses.
Keyword ：
Fracture energy Metallic glass Molecular dynamics simulation Pressure-promoted thermal rejuvenation
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| GB/T 7714 | Li, Hong , Jin, Cheng-Gang , Sha, Zhen-Dong . The effect of pressure-promoted thermal rejuvenation on the fracture energy of metallic glasses [J]. | JOURNAL OF NON-CRYSTALLINE SOLIDS , 2022 , 590 . |
| MLA | Li, Hong et al. "The effect of pressure-promoted thermal rejuvenation on the fracture energy of metallic glasses" . | JOURNAL OF NON-CRYSTALLINE SOLIDS 590 (2022) . |
| APA | Li, Hong , Jin, Cheng-Gang , Sha, Zhen-Dong . The effect of pressure-promoted thermal rejuvenation on the fracture energy of metallic glasses . | JOURNAL OF NON-CRYSTALLINE SOLIDS , 2022 , 590 . |
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Abstract ：
The potential application of metallic glasses (MGs) as structural materials demands accurate measurements of their toughness and the understanding of the underlying factors affecting it. Currently, it is challenging to precisely measure the toughness of MGs, especially ductile MGs. Measured toughness values are widely scattered, even for MGs with identical compositions. That is attributed to the combined effect of intrinsic and extrinsic factors including processing, sample geometries, and loading conditions. A fundamental understanding of the influences of these elements is thus of great significance. In the present study, molecular dynamics simulations are performed to investigate the influence of intrinsic and extrinsic effects on the fracture toughness of CuZr MGs. In particular, focused is placed on the effects of cooling rate, notch shape and size, strain rate, and temperature. The results indicate that the fracture toughness of a MG scales with the cooling rate used to prepare it. This is attributed to increased free volume content generated at high cooling rates, which enhances plastic deformation and amplifies the associated energy dissipation during plastic deformation events. Fracture toughness also increases with the strain rate, arguably due to strain rate-induced crack extension delay. Overall, the results demonstrate that the largest fracture toughness are achieved when MG samples are fabricated at high cooling rates and subjected to high strain rate deformation. In addition, results suggest that the fracture toughness decreases with increasing temperature, due to the significant decrease in strength. The correlations revealed between these crucial intrinsic and extrinsic parameters and the calculated MG fracture toughness support the development of a framework to understand the root of the discrepancies in the measurement of the toughness of MGs and provide insights into the design of tough MGs for structural applications.
Keyword ：
Fracture energy Metallic glass Molecular dynamics simulation
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| GB/T 7714 | Li, Hong , Pei, Qing-Xiang , Sha, Zhen-Dong et al. Intrinsic and extrinsic effects on the fracture toughness of ductile metallic glasses [J]. | MECHANICS OF MATERIALS , 2021 , 162 . |
| MLA | Li, Hong et al. "Intrinsic and extrinsic effects on the fracture toughness of ductile metallic glasses" . | MECHANICS OF MATERIALS 162 (2021) . |
| APA | Li, Hong , Pei, Qing-Xiang , Sha, Zhen-Dong , Branicio, Paulo S. . Intrinsic and extrinsic effects on the fracture toughness of ductile metallic glasses . | MECHANICS OF MATERIALS , 2021 , 162 . |
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Abstract ：
Metallic glasses (MGs) are often perceived as quintessential structural materials. However, the widespread application of MGs is hindered primarily by their limited glass-forming ability (GFA) for the manufacture of large-scale MGs. In this work, a two-step fused machine learning (ML) approach is proposed, aiming to provide an efficient tactic for the precise prediction of MGs with robust GFA. In our ML framework, alloy compositions are the only required inputs. Moreover, the dataset comprises alloys that can and cannot be cast into MGs. This departs from the conventional ML approach utilizing only a correct set of training data (i.e. alloys that can cast into MGs). The fusion algorithm is also employed to further improve the perfor-mance of ML approach. The critical casting sizes predicted by our ML model are in good agreement with those reported in experiments. This work has extensive implications for the design of bulk MGs with superior GFA. (c) 2021 Elsevier B.V. All rights reserved.
Keyword ：
Glass-forming ability Good glass former Machine learning Metallic glass
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| GB/T 7714 | Zhang, Y. X. , Xing, G. C. , Sha, Z. D. et al. A two-step fused machine learning approach for the prediction of glass-forming ability of metallic glasses [J]. | JOURNAL OF ALLOYS AND COMPOUNDS , 2021 , 875 . |
| MLA | Zhang, Y. X. et al. "A two-step fused machine learning approach for the prediction of glass-forming ability of metallic glasses" . | JOURNAL OF ALLOYS AND COMPOUNDS 875 (2021) . |
| APA | Zhang, Y. X. , Xing, G. C. , Sha, Z. D. , Poh, L. H. . A two-step fused machine learning approach for the prediction of glass-forming ability of metallic glasses . | JOURNAL OF ALLOYS AND COMPOUNDS , 2021 , 875 . |
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Abstract ：
The pressure-promoted thermal rejuvenation is a promising approach for improving the macroscopic plasticity of metallic glasses (MGs). Here, molecular dynamics simulations have been performed to investigate the atomic structure and mechanical behavior of the rejuvenated MGs with pressure-promoted thermal processing. The effects of annealing temperatures and pressures are investigated, with results suggesting that the pressure has a significant influence on the deformation and failure mechanism of the rejuvenated MGs. The MGs can be rejuvenated either by the application of negative pressures with the low annealing temperature, or by the application of positive pressures with the high annealing temperature. Accompanied by the rejuvenation, a transition in failure mode from localized shear banding to homogeneous plastic deformation occurs due to the higher-energy glassy state induced by the thermal-pressure loading process. The present study provides important insights into the atomic-level structures of the rejuvenated MGs, as well as useful guidelines for the design of strong and high plastic MGs. © 2020 Elsevier B.V.
Keyword ：
Annealing Endocrinology Failure (mechanical) Glass Metallic glass Molecular dynamics
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| GB/T 7714 | Li, S , Zhang, J.C , Sha, Z.D . Mechanical behavior of metallic glasses with pressure-promoted thermal rejuvenation [J]. | Journal of Alloys and Compounds , 2020 , 848 . |
| MLA | Li, S et al. "Mechanical behavior of metallic glasses with pressure-promoted thermal rejuvenation" . | Journal of Alloys and Compounds 848 (2020) . |
| APA | Li, S , Zhang, J.C , Sha, Z.D . Mechanical behavior of metallic glasses with pressure-promoted thermal rejuvenation . | Journal of Alloys and Compounds , 2020 , 848 . |
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Abstract ：
Using molecular dynamics (MD) simulations, we investigate the mechanical properties of hexagonal BCN monolayer, a newly synthesized two-dimensional material with an atom ratio of B/C/N = 1:1:1. The Tersoff potential is modified to get good agreement between predicted and measured fracture strengths of graphene. With this modified Tersoff potential, we perform extensive MD simulations to study the effect of temperature, strain rate and vacancy defect on the mechanical properties of h-BCN. It is found that h-BCN is a strong material with fracture strength of 81.4-93.5 GPa, albeit similar to 35% lower than that of graphene. Similar to graphene, temperature has strong effect on the mechanical properties of h-BCN. As the temperature increases from 10 K to 1300 K, the fracture strength and strain of h-BCN drops by 55% and 62%, respectively. The strain rate is found to have a moderate effect. When the strain rate increases from 0.00002 to 0.0125 ps(-1), the fracture strength and strain of h-BCN increases 6.1% and 12%, respectively. As for the atomic defect, a very small concentration (0.028%) of vacancy in h-BCN is able to cause a 28% reduction in fracture strength and a 35.5% reduction in fracture strain. These findings have significance for its future applications in nanodevices. (C) 2019 Elsevier B.V. All rights reserved.
Keyword ：
Graphene h-BCN Mechanical properties Molecular dynamics
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| GB/T 7714 | Zhang, Ying-Yan , Pei, Qing-Xiang , Sha, Zhen-Dong et al. A molecular dynamics study of the mechanical properties of h-BCN monolayer using a modified Tersoff interatomic potential [J]. | PHYSICS LETTERS A , 2019 , 383 (23) : 2821-2827 . |
| MLA | Zhang, Ying-Yan et al. "A molecular dynamics study of the mechanical properties of h-BCN monolayer using a modified Tersoff interatomic potential" . | PHYSICS LETTERS A 383 . 23 (2019) : 2821-2827 . |
| APA | Zhang, Ying-Yan , Pei, Qing-Xiang , Sha, Zhen-Dong , Zhang, Yong-Wei . A molecular dynamics study of the mechanical properties of h-BCN monolayer using a modified Tersoff interatomic potential . | PHYSICS LETTERS A , 2019 , 383 (23) , 2821-2827 . |
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Abstract ：
Organic-inorganic hybrid metal-halide perovskites, such as methylammonium lead iodide, have emerged as amazing semiconductors with immense potential in thin film photovoltaic owing to their impressive diffusion lengths. However, the instability of these perovskites in ambient air, due to the presence of hydrophilic and volatile organic cation, hinders their further commercialization. Although low-dimensional perovskite solar cells (PSCs) show better stability than conventional three-dimensional (3D) devices, the low power conversion efficiency (PCE) is delivered, due to the decline of carrier mobility and diffusion length. Here, a large organic cation, tert-butylammonium (t-BA), is incorporated into the 3D perovskite, which not only enhances the crystal stability, but also greatly reduces the trap density and improves the mobility of the perovskite film, leading to similar to 1.8 mu m electron and hole diffusion lengths. High-performance PSCs based on t-BA(0.1)[Cs-0.05(FA(0.83)MA(0.17))(0.95)](0.9)Pb(I0.83Br0.17)(3) with champion PCEs of 20.62% (19.8% +/- 0.4%) for 0.04 cm(2) and 14.54% for 20.8 cm(2) are demonstrated. More importantly, with humidity of 45-55%, the solar cells could sustain 80% of their "post burn-in" PCE after continuous working under light (AM1.5G, 100 mW cm(-2)) in air for 1174 h. This lifetime is 63% longer than that (718 h) of the control Cs-0.05(FA(0.83)MA(0.17))(0.95)Pb(I0.83Br0.17)(3)PSCs.
Keyword ：
Diffusion length High performance Perovskite solar cells Stability
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| GB/T 7714 | Liang, Chao , Zhao, Dandan , Li, Pengwei et al. Simultaneously boost diffusion length and stability of perovskite for high performance solar cells [J]. | NANO ENERGY , 2019 , 59 : 721-729 . |
| MLA | Liang, Chao et al. "Simultaneously boost diffusion length and stability of perovskite for high performance solar cells" . | NANO ENERGY 59 (2019) : 721-729 . |
| APA | Liang, Chao , Zhao, Dandan , Li, Pengwei , Wu, Bo , Gu, Hao , Zhang, Jiacheng et al. Simultaneously boost diffusion length and stability of perovskite for high performance solar cells . | NANO ENERGY , 2019 , 59 , 721-729 . |
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Abstract ：
While many experiments and simulations on metallic glasses (MGs) have focused on their tensile ductility under monotonic loading, the fatigue mechanisms of MGs under cyclic loading still remain largely elusive. Here we perform molecular dynamics (MD) and finite element simulations of tension-compression fatigue tests in MGs to elucidate their fatigue mechanisms with focus on the sample size effect. Shear band (SB) thickening is found to be the inherent fatigue mechanism for nanoscale MGs. The difference in fatigue mechanisms between macroscopic and nanoscale MGs originates from whether the SB forms partially or fully through the cross-section of the specimen. Furthermore, a qualitative investigation of the sample size effect suggests that small sample size increases the fatigue life while large sample size promotes cyclic softening and necking. Our observations on the size-dependent fatigue behavior can be rationalized by the Gurson model and the concept of surface tension of the nanovoids. The present study sheds light on the fatigue mechanisms of MGs and can be useful in interpreting previous experimental results. (C) 2017 Elsevier Ltd. All rights reserved.
Keyword ：
Fatigue mechanism Finite element modeling Metallic glasses Molecular dynamics simulations
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| GB/T 7714 | Sha, Zhendong , Wong, Wei Hin , Pei, Qingxiang et al. Atomistic origin of size effects in fatigue behavior of metallic glasses [J]. | JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS , 2017 , 104 : 84-95 . |
| MLA | Sha, Zhendong et al. "Atomistic origin of size effects in fatigue behavior of metallic glasses" . | JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS 104 (2017) : 84-95 . |
| APA | Sha, Zhendong , Wong, Wei Hin , Pei, Qingxiang , Branicio, Paulo Sergio , Liu, Zishun , Wang, Tiejun et al. Atomistic origin of size effects in fatigue behavior of metallic glasses . | JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS , 2017 , 104 , 84-95 . |
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