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Cooperative effect of Cr and Al elements on passivation enhancement of eutectic high-entropy alloy AlCoCrFeNi_(2.1)with precipitates

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Journal of Materials Science & Technology 2023年第5期136卷 97-108页

作者： Xiaotian Duan Tiezhuang Han Xiao Guan Yuning Wang Huhu Su kaisheng ming Jing Wang Shijian Zheng State Key Laboratory of Reliability and Intelligence of Electrical Equipment Hebei University of TechnologyTianjin 300130China School of Material Science and Engineering Hebei University of TechnologyTianjin 300130China

In conventional corrosion-resistant alloys,precipitation usually reduces corrosion resistance severely by weakening passive films *** this work,we found that the aging-treated AlCoCrFeNi_(2.1)sam-ples,which have abundant nanosized L 12 and body-centered cubic(BCC)precipitates in the lamellar face-centered cubic(FCC)and B2 phases,displayed better corrosion resistance than solution-treated AlCoCrFeNi_(2.1)samples without *** the AlCoCrFeNi_(2.1)alloy,the FCC phase with L1_(2)precipi-tates and the B2 phase with BCC precipitates were protected by passive films enriched with Cr and Al elements,***,the Al-rich passive film of the B2 phase was less stable than the Cr-rich passive film of the FCC phase,so B2 phase dissolved *** Cr-rich passive film of the FCC phase remained stable with the formation of Al-rich L1_(2)precipitates inside the phase because those precipitates with the size of∼5 nm were too small to affect the composition of the Cr-rich passive *** formation of Cr-rich BCC precipitates within the B2 phase increased the content of the Al element inside the phase,improving the stability of Al-rich passive film on the B2 ***,BCC precip-itates with the size of∼30 nm were protected by Cr-rich passive film,which could inhibit the expansion of corrosion ***,the corrosion resistance of eutectic high-entropy alloy AlCoCrFeN 2.1 was unprece-dentedly enhanced by the precipitation of BCC *** study could provide an attractive strategy for designing high-entropy alloys with excellent corrosion resistance and high strength.

关键词： Eutectic high-entropy alloy Passive film Corrosion resistance Precipitates TEM

Intermediate Temperature Fatigue Induced Precipitation and Associated Corrosion in CrMnFeCoNi High Entropy Alloy

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Acta Metallurgica Sinica(English Letters) 2023年第11期36卷 1857-1869页

作者： Tiezhuang Han Jing Wang Bo Li Shuang Li kaisheng ming Fucheng Wang Bin Miao Shijian Zheng Tianjin Key Laboratory of Materials Laminating Fabrication and Interface Control Technology School of Materials Science and EngineeringHebei University of TechnologyTianjin300401China

Understanding the corrosion behavior of high entropy alloys(HEAs)after intermediate temperature fatigue is critical to prevent their catastrophic failures from the reduction of corrosion ***,we investigated the corrosion behavior of CrMnFeCoNi HEA after 500℃ fatigue test with strain amplitudes of 0.2%and 0.5%.The intermediate temperature fatigue induced two types of precipitates,which were determined as Cr-richσphase and NiMn-rich L10 *** strain amplitude not only promoted precipitates generations but also spread the nucleation sites from intergranular to both intergranular and ***,we found that the deterioration in corrosion resistance of the alloy was derived from the increase of precipitates,which destroyed the stability of the passive *** above results revealed that intermediate temperature fatigue impaired the stabilization of the solid solution state and subsequent corrosion resistance of CrMnFeCoNi HEA,where the higher strain amplitude led to more precipitates and more severe corrosion.

关键词： High entropy alloy Corrosion Intermediate temperature fatigue Phase stability Precipitate

In situ observation of transmission and reflection of dislocations at twin boundary in CoCrNi alloys

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Science China(Technological Sciences) 2021年第2期64卷 407-413页

作者： LIANG YanXiang YANG XiaoFang ming kaisheng XIANG ShiHua LIU Qing International Joint Laboratory for Light Alloys(Ministry of Education) College of Materials Science and EngineeringChongqing UniversityChongqing 400044China Key Laboratory of Aerospace Materials and Performance(Ministry of Education) School of Materials Science and EngineeringBeihang UniversityBeijing 100191China

The deformation mechanism of CoCrNi alloy with high density of annealing twins was studied by in situ transmission electron microscopy. Dislocation transmission and reflection at the twin boundary were observed during in situ loading. We characterized these reaction processes by combining TEM, dislocation theory and crystallography of twin. Twin boundary not only strengthens the material by impeding the motion of dislocation, but also acts as dislocation source to produce large of slip bands. These processes generate large of slip bands to accommodate the plastic deformation or strengthening material.

关键词： dislocation transmission reflection TEM CoCrNi alloys

High-temperature strength-coercivity balance in a FeCo-based soft magnetic alloy via magnetic nanoprecipitates

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Journal of Materials Science & Technology 2021年第22期81卷 36-42页

作者： kaisheng ming Shuimiao Jiang Xiaoyuan Niu Bo Li Xiaofang Bi Shijian Zheng State Key Laboratory of Reliability and Intelligence of Electrical Equipment Hebei University of TechnologyTianjin300130China Tianjin Key Laboratory of Materials Laminating Fabrication and Interface Control Technology School of Materials Science and EngineeringHebei University of TechnologyTianjin300130China Key Laboratory of Aerospace Materials and Performance(Ministry of Education) School of Materials Science and EngineeringBeihang UniversityBeijing100191China School of Chemical Engineering and Technology Hebei University of TechnologyTianjin300130China

Precipitation strengthening is an effective approach to enhance the strength of soft magnetic alloys for applications at high temperatures,while inevitably results in deterioration in coercivity due to the pinning effect on the domain wall ***,we realize a good combination of high-temperature strength and ductility(ultimate tensile strength of 564 MPa and elongation of~20%,respectively)as well as low coercivity(6.97 Oe)of FeCo-2V-0.3Cr-0.2Mo soft magnetic alloy through introducing high-density magnetic *** magnetic nanoprecipitates are characterized by FeCo-based phase with disordered body-centered cubic structure,which enables the alloy to have a low *** addition,these nanoprecipitates can impede the dislocation motion and suppress the brittle fracture,which lead to a high tensile strength and *** work provides a guideline to enhance strength and ductility while maintaining low coercivity in soft magnetic alloys via magnetic nanoprecipitates.

关键词： FeCo-based soft magnetic alloys Strength Ductility Coercivity Magnetic nanoprecipitates

晶界偏析以及界面相和纳米晶材料力学性能的调控

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材料研究学报 2023年第5期37卷 321-331页

作者：姜水淼明开胜郑士建河北工业大学材料科学与工程学院天津300401 天津市材料层状复合与界面控制技术重点实验室天津300401

介绍晶界偏析理论并总结了三种经典平衡偏析理论模型,简述晶界偏析工程理论和晶界偏析对材料力学性能的影响、讨论晶界偏析与界面相的关系并详细阐述了“界面相”。根据原子尺度界面结构特征将界面相分为六类,介绍了由晶界热力学决定的... 详细信息

介绍晶界偏析理论并总结了三种经典平衡偏析理论模型,简述晶界偏析工程理论和晶界偏析对材料力学性能的影响、讨论晶界偏析与界面相的关系并详细阐述了“界面相”。根据原子尺度界面结构特征将界面相分为六类,介绍了由晶界热力学决定的界面相转变。界面相转变后在晶界处形成新结构,而新界面结构根据其不同性质既可能提高材料性能,也可能产生不利的影响。晶界处的Ⅵ型界面相(如非晶晶间膜)抑制裂纹形核和降低晶界损伤,而削弱晶界处原子键强度的Ⅱ型界面相和Ⅲ型界面相(如Ni合金晶界处成分为Bi的双原子层界面相)产生晶界脆化。同时,纳米晶金属材料的强度高但是热稳定性和塑性较差,一直是研究的热点。界面相使晶界能显著降低和钉扎晶界而优于晶界偏析,因此界面相能显著提高纳米晶金属材料的热稳定性。而非晶晶间膜(Ⅵ型界面相)作为位错的形核点和吸收体,可提高纳米材料的延展性。同时,非晶晶间膜能提高晶界抗剪切能力,抑制纳米晶金属材料的晶粒滑动和旋转,从而进一步提高纳米晶金属材料的强塑性。最后,总结了晶界偏析和界面相对材料性能的调控并展望了以后的发展。

关键词：评述材料科学基础学科晶界偏析界面相纳米晶金属材料热稳定性力学性能

An improved initial rotor position estimation method using high-frequency pulsating voltage injection for PMSM

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Defence Technology（防务技术） 2024年第3期33卷 19-29页

作者： Yang Jiang ming Cheng School of Electrical Engineering Southeast UniversityNanjing 210096China

High frequency pulsating voltage injection method is a good candidate for detecting the initial rotor position of permanent magnet synchronous ***,traditional methods require a large number of filters,which leads to the deterioration of system stability and dynamic *** order to solve these problems,a new signal demodulation method is proposed in this *** proposed new method can directly obtain the amplitude of high-frequency current,thus eliminating the use of filters,improving system stability and dynamic performance and saving the work of adjusting filter *** addition,a new magnetic polarity detection method is proposed,which is robust to current measurement ***,experiments verify the effectiveness of the method.

关键词： Initial position detection Signal demodulation algorithm Magnetic polarity detection Filter elimination

A Deep Learning Method for Computing Eigenvalues of the Fractional Schrödinger Operator

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Journal of Systems Science & Complexity 2024年第2期37卷 391-412页

作者： GUO Yixiao ming Pingbing LSEC Institute of Computational Mathematics and Scientific/Engineering ComputingAcademy of Mathematics and Systems ScienceChinese Academy of SciencesBeijing 100190China School of Mathematical Sciences University of Chinese Academy of SciencesBeijing 100049China

The authors present a novel deep learning method for computing eigenvalues of the fractional Schrödinger *** proposed approach combines a newly developed loss function with an innovative neural network architecture that incorporates prior knowledge of the *** improvements enable the proposed method to handle both high-dimensional problems and problems posed on irregular bounded *** authors successfully compute up to the first 30 eigenvalues for various fractional Schrödinger *** an application,the authors share a conjecture to the fractional order isospectral problem that has not yet been studied.

关键词： Eigenvalue problem deep learning fractional Schrödinger operator isospectral problem

Selective nano-buckling improves the performance of graphene logic transistors

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National Science Review 2024年第2期11卷 95-96页

作者： Tong Yang ming Yang Department of Applied Physics The Hong Kong Polytechnic University Research Centre for Nanoscience and Nanotechnology The Hong Kong Polytechnic University

The massive integration of silicon-based transistors into modern electronic devices greatly increases power consumption and heat generation/dissipation[1]. In this concern, transistors based on atomically-thin graphene that exhibit high electric and thermoelectric conductivities with negligible contact resistance,

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Exploring a Promising Region and Enhancing Decision Space Diversity for Multimodal Multi-Objective Optimization

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Tsinghua Science and Technology 2024年第2期29卷 325-342页

作者： Fei ming Wenyin Gong School of Computer Science China University of GeosciencesWuhan 430074China

During the past decade,research efforts have been gradually directed to the widely existing yet less noticed multimodal multi-objective optimization problems(MMOPs)in the multi-objective optimization ***,researchers have begun to investigate enhancing the decision space diversity and preserving valuable dominated solutions to overcome the shortage caused by a preference for objective space ***,many existing methods still have limitations,such as giving unduly high priorities to convergence and insufficient ability to enhance decision space *** overcome these shortcomings,this article aims to explore a promising region(PR)and enhance the decision space diversity for handling *** traditional methods,we propose the use of non-dominated solutions to determine a limited region in the PR in the decision space,where the Pareto sets(PSs)are included,and explore this region to assist in solving ***,we develop a novel neighbor distance measure that is more suitable for the complex geometry of PSs in the decision space than the crowding *** on the above methods,we propose a novel dual-population-based coevolutionary *** studies on three benchmark test suites demonstrates that our proposed methods can achieve promising performance and versatility on different *** effectiveness of the proposed neighbor distance has also been justified through comparisons with crowding distance methods.

关键词： multimodal multi-objective optimization evolutionary algorithms promising region neighbor distance decision space coevolution