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On the thermodynamics of plasticity during quasi-isentropic compression of metallic glass

Matter and Radiation at Extremes 2024年第2期9卷 74-89页

作者： Kaiguo Chen Bo Chen yinan cui Yuying Yu Jidong Yu Huayun Geng Dongdong Kang Jianhua Wu Yao Shen Jiayu Dai College of Science National University of Defense TechnologyChangsha 410073People’s Republic of China Hunan Key Laboratory of Extreme Matter and Applications National University of Defense TechnologyChangsha 410073People’s Republic of China Applied Mechanics Laboratory Department of Engineering MechanicsSchool of AerospaceTsinghua UniversityBeijing 100084People’s Republic of China Institute of Fluid Physics China Academy of Engineering PhysicsMianyangPeople’s Republic of China Department of Material Science and Technology Shanghai Jiao Tong UniversityShanghaiPeople’s Republic of China

Entropy production in quasi-isentropic compression (QIC) is critically important for understanding the properties of materials under extremeconditions. However, the origin and accurate quantification of entropy in this situation remain long-standing challenges. In this work, a framework is established for the quantification of entropy production and partition, and their relation to microstructural change in QIC. Cu50Zr50is taken as a model material, and its compression is simulated by molecular dynamics. On the basis of atomistic simulation-informed physicalproperties and free energy, the thermodynamic path is recovered, and the entropy production and its relation to microstructural change aresuccessfully quantified by the proposed framework. Contrary to intuition, entropy production during QIC of metallic glasses is relativelyinsensitive to the strain rate ˙γ when ˙γ ranges from 7.5 × 10^(8) to 2 × 10^(9)/s, which are values reachable in QIC experiments, with a magnitudeof the order of 10^(−2)kB/atom per GPa. However, when ˙γ is extremely high (>2 × 10^(9)/s), a notable increase in entropy production rate with˙γ is observed. The Taylor–Quinney factor is found to vary with strain but not with strain rate in the simulated regime. It is demonstrated thatentropy production is dominated by the configurational part, compared with the vibrational part. In the rate-insensitive regime, the increase inconfigurational entropy exhibits a linear relation to the Shannon-entropic quantification of microstructural change, and a stretched exponential relation to the Taylor–Quinney factor. The quantification of entropy is expected to provide thermodynamic insights into the fundamentalrelation between microstructure evolution and plastic dissipation.

关键词： entropy metallic regime

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辐照缺陷装饰位错是否会导致硬化?

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Acta Mechanica Sinica 2024年第2期40卷 259-267页

作者：崔嵬刘伟崔一南 Navigation and Control Technology Research Institute of China North Industries Group Corporation Limited Beijing100089China School of Materials Science and Engineering Tsinghua UniversityBeijing100084China Applied Mechanics Lab. School of Aerospace EngineeringTsinghua UniversityBeijing100084China

纳米尺寸的辐照缺陷常常会在位错线附近聚集,形成装饰效应.研究者通常采用级联诱导源硬化模型描述装饰效应引起的辐照硬化.本研究工作发现不可动辐照缺陷装饰位错会导致辐照硬化,硬化程度与理论模型预测一致.然而,当装饰辐照缺陷可动时... 详细信息

纳米尺寸的辐照缺陷常常会在位错线附近聚集,形成装饰效应.研究者通常采用级联诱导源硬化模型描述装饰效应引起的辐照硬化.本研究工作发现不可动辐照缺陷装饰位错会导致辐照硬化,硬化程度与理论模型预测一致.然而,当装饰辐照缺陷可动时,则不发生辐照硬化,甚至发生软化,这种硬化消失是由于位错环始终处于与位错线相互作用力近似为零的区域,并与位错线发生关联运动.该工作带来了对辐照缺陷装饰效应和辐照硬化的新理解.

关键词：相互作用力辐照硬化辐照缺陷装饰效应硬化模型位错环纳米尺寸模型预测

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Number of Solitons Emerged in the Initial Profile of Shallow Water Using Convolutional Neural Networks

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Journal of Systems Science & Complexity 2024年第2期37卷 463-479页

作者： WANG Zhen cui Shikun School of Mathematical Sciences Dalian University of TechnologyDalian 116024China School of Mathematical Sciences Beihang UniversityBeijing 100191China

The soliton resolution conjecture proposes that the initial value problem can evolve into a dispersion part and a soliton part.However,the problem of determining the number of solitons that form in a given initial profile remains unsolved,except for a few specific cases.In this paper,the authors use the deep learning method to predict the number of solitons in a given initial value of the Korteweg-de Vries(KdV)equation.By leveraging the analytical relationship between Asech^(2)(x)initial values and the number of solitons,the authors train a Convolutional Neural Network(CNN)that can accurately identify the soliton count from spatio-temporal data.The trained neural network is capable of predicting the number of solitons with other given initial values without any additional assistance.Through extensive calculations,the authors demonstrate the effectiveness and high performance of the proposed method.

关键词： Convolutional neural network deep learning method KdV equation soliton

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Ultrafast micro/nano-manufacturing of metastable materials for energy

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National Science Review 2024年第4期11卷 283-298页

作者： Xiaoya cui Yanchang Liu Yanan Chen School of Materials Science and Engineering Key Laboratory of Advanced Ceramics and Machining Technology(Ministry of Education) and Tianjin Key Laboratory of Composite and Functional MaterialsTianjin University Ministry of Education Key Laboratory of Protein Sciences School of Life SciencesTsinghua University

The structural engineering of metastable nanomaterials with abundant defects has attracted much attention in energy-related fields. The high-temperature shock(HTS) technique, as a rapidly developing and advanced synthesis strategy, offers significant potential for the rational design and fabrication of high-quality nanocatalysts in an ultrafast, scalable, controllable and eco-friendly way. In this review, we provide an overview of various metastable micro-and nanomaterials synthesized via HTS, including single metallic and bimetallic nanostructures, high entropy alloys, metal compounds(e.g. metal oxides) and carbon nanomaterials. Note that HTS provides a new research dimension for nanostructures, i.e. kinetic modulation. Furthermore, we summarize the application of HTS—as supporting films for transmission electron microscopy grids—in the structural engineering of 2D materials, which is vital for the direct imaging of metastable materials. Finally, we discuss the potential future applications of high-throughput and liquid-phase HTS strategies for non-equilibrium micro/nano-manufacturing beyond energy-related fields.It is believed that this emerging research field will bring new opportunities to the development of nanoscience and nanotechnology in both fundamental and practical aspects.

关键词： high-temperature shock technique defect engineering metastable phase kinetic modulation non-equilibrium micro/nano-manufacturing

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Multi-Sensor Fusion Adaptive Estimation for Nonlinear Under-observed System with Multiplicative Noise

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Chinese Journal of Electronics 2024年第1期33卷 282-292页

作者： Yongpeng cui Xiaojun SUN School of Electronic Engineering Heilongjiang University Key Laboratory of Information Fusion Estimation and Detection

The adaptive fusion estimation problem was studied for the multi-sensor nonlinear under-observed systems with multiplicative noise. A one-step predictor with state update equations was designed for the virtual state with virtual noise first of all. An extended incremental Kalman filter(EIKF) was then proposed for the nonlinear under-observed systems. Furthermore, an adaptive filtering method was given for optimization. The fusion adaptive incremental Kalman filter weighted by scalar was finally proposed. The comparison analysis was made to verify the optimization of the state estimation using adaptive filtering method in the filtering process.

关键词： Information fusion Multiplicative noise Under-observed systems Adaptive filtering Incremental filtering

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析出硬化微观机制及连续化模型

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中国科学：物理学、力学、天文学 2024年第5期54卷 21-34页

作者：崔爱雅崔一南清华大学航天航空学院应用力学教育部重点实验室北京100084

析出硬化作为提升合金强度的主要方法,在低碳钢、镍基合金等工程合金中得到广泛应用.理解析出硬化效应并发展相应的理论模型对合金的强韧化设计至关重要.尽管研究者很早就开始关注析出硬化效应,并基于线张力理论发展了一系列经典的析出... 详细信息

析出硬化作为提升合金强度的主要方法,在低碳钢、镍基合金等工程合金中得到广泛应用.理解析出硬化效应并发展相应的理论模型对合金的强韧化设计至关重要.尽管研究者很早就开始关注析出硬化效应,并基于线张力理论发展了一系列经典的析出硬化模型,但目前仍存在由于对析出硬化微观机理等认识不够深入导致硬化模型误用的情况.鲜有综述论文系统阐述这些强化机制在微观物理过程上存在着怎样的关联关系,以及如何正确选择不同的析出硬化模型.为此,本文从位错-析出相相互作用的微观物理过程出发,通过分析长程作用和短程作用,深入探讨了基于线张力的连续化硬化模型的适用范围.同时详细介绍了不同的强化概念与位错剪切机制和Orowan绕过机制的关联关系,并分析了不同情况下位错-析出相间作用的主导机制如何随共格析出相的尺寸变化而转变.本文的工作对于深入理解析出硬化机理,有效描述析出硬化效应,指导合金设计等具有重要的参考价值.

关键词：析出硬化微观机理线张力理论位错剪切机制 Orowan绕过机制

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“Buckets effect”in the kinetics of electrocatalytic reactions

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Journal of Energy Chemistry 2024年第2期89卷 388-396,I0010页

作者： Haowen cui Yan-Xia Chen Hefei National Laboratory for Physical Sciences at Microscale Department of Chemical PhysicsUniversity of Science and Technology of ChinaHefei 230026AnhuiChina

In this study,we systematically investigated the effect of proton concentration on the kinetics of the oxygen reduction reaction(ORR)on Pt(111)in acidic solutions.Experimental results demonstrate a rectangular hyperbolic relationship,i.e.,the ORR current excluding the effect of other variables increases with proton concentration and then tends to a constant value.We consider that this is caused by the limitation of ORR kinetics by the trace oxygen concentration in the solution,which determines the upper limit of ORR kinetics.A model of effective concentration is further proposed for rectangular hyperbolic relationships:when the reactant concentration is high enough to reach a critical saturation concentration,the effective reactant concentration will become a constant value.This could be due to the limited concentration of a certain reactant for reactions involving more than one reactant or the limited number of active sites available on the catalyst.Our study provides new insights into the kinetics of electrocatalytic reactions,and it is important for the proper evaluation of catalyst activity and the study of structureperformance relationships.

关键词： Oxygen reduction reaction Kinetics Zero order Rectangular hyperbolic relationship pH effect

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Asymmetric Hydrogenation of Phenanthridines with Chiral Boranes

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Chinese Journal of Chemistry 2024年第6期42卷 631-635页

作者： Guangyu cui Xiangqing Feng Haifeng Du Beijing National Laboratory for Molecular Sciences CAS Key Laboratory of Molecular Recognition and FunctionInstitute of ChemistryChinese Academy of SciencesBeijing100190 China University of Chinese Academy of Sciences Beijing100049 China

The asymmetric hydrogenation of N-heteroarenes provides an efficient method for the synthesis of optically active cyclic secondary amines.In this paper,we described an asymmetric hydrogenation of phenanthridines using a chiral mono-alkene-derived borane.A variety of dihydrophenanthridines were furnished in high yields with up to 93%ee.The current catalytic system was very sensitive for the steric hindrance of phenanthridines.Bulky substituents at one phenyl group of phenanthridines were required to obtain the high enantioselectivity.But large substituents on the carbon of the C=N bonds would diminish the reactivity sharply.

关键词： Asymmetric catalysis Hydrogenation Nitrogen heterocycles Phenanthridines Frustrated Lewis pairs Chiral boranes

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Nano-effect enhanced cooperative luminescence of Yb^(3+) clusters in bulk materials

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Journal of Rare Earths 2024年第3期42卷 473-478,I0002页

作者： Daguang Li Jiahao cui Yanhui Dong Hao cui Dan Zhao Weiping Qin State Key Laboratory on Integrated Optoelectronics College of Electronic Science and EngineeringJilin UniversityChangchun130012China

In order to improve the multi-ion cooperative transition, we proposed and exploited a novel nanoscale effect, namely the nanoshell effect in bulk materials. Based on the effect, an optimal material structure was designed by coating the surfaces of Ca F_(2):Yb^(3+)micron size particles with ZrO_(2). An about 2 times higher intensity of cooperative luminescence is observed upon laser excitation at 980 nm. Dynamical analysis exhibits that the novel effect plays a key role in improving the performance of cooperative transitions. Our results also suggest that the nanoshell effect in bulk materials is likely to be significant in some special cases, which have not been reported yet in the literature.

关键词： Yb^(3+)cluster ZrO_(2) Nanoshell Enhancement Cooperative luminescence Rare earths

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Influence of ammonium sulfate on the corrosion behavior of AZ31 magnesium alloy in chloride environment

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Journal of Magnesium and Alloys 2024年第3期12卷 1082-1101页

作者： Feng Ge Zhongyu cui Yue Liu Li Lei Xin Wang Hongzhi cui School of Materials Science and Engineering Ocean University of ChinaQingdao 266100China Beijing National Innovation Institute of Lightweight Ltd.Beijing 101499China

Electrochemical corrosion of AZ31 magnesium alloy in the NH_(4)^(+)-SO_(4)2−-Cl−environment is studied.Effect of NH_(4)^(+)overshadows that of Cl−as the(NH_(4))_(2)SO_(4) concentration is 0.005 M or higher,yielding an evolution from localized corrosion to uniform corrosion.Acceleration effect of NH_(4)^(+)can be attributed to that(i)NH_(4)^(+)dissolves the inner MgO and hinders the precipitation of Mg(OH)_(2) and(ii)the buffering ability of NH_(4)^(+)provides H+,enhances the hydrogen evolution,and expedites the corrosion process.The latter is demonstrated as the dominant factor with the results in unbuffered and buffered environments.The severe corrosion and hydrogen process in NH_(4)^(+)-containing solution results in a high Hads coverage and yields an inductive loop within the low frequency.Meanwhile,SO_(4)^(2−)is helpful in generating cracked but partially protective corrosion products,while Cl−could broaden the corrosion area beneath the corrosion product.

关键词： Magnesium alloy Ammonium corrosion Electrochemical kinetic parameter Anodic dissolution.

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