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Effect of magnetic field on dislocation morphology and precipitation behaviour in ultrafine-grained 7075 aluminium alloy

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Journal of Materials Science & Technology 2021年第34期93卷 128-146页

作者： Jun luo hongyun luo Tianshu Zhao Runze Wang Key Laboratory of Aerospace Materials and Performance(Ministry of Education) School of Materials Science and EngineeringBeihang UniversityBeijing 100191China Beijing Key Laboratory of Advanced Nuclear Materials and Physics Beihang UniversityBeijing 100191China Beijing Advanced Innovation Centre for Biomedical Engineering Beihang UniversityBeijing 100191China

The influence of magnetic field(1 T)on dislocation morphology and precipitation behaviour of ultrafinegrained(UFG)Al 7075 alloy was investigated after ageing from 90 to 200℃ via wide angle X-ray scattering(WAXS),small angle X-ray scattering(SAXS),and transmission electron microscopy(TEM).Experimental results reveal that the improved precipitation kinetics of alloys in the thickness plane(denoted as sample II)as compared to those in the rolling plane(denoted as sample I),which arises due to a higher dislocation density(morphology of dislocation cells)of the thickness plane than that of the rolling plane(morphology of dislocations and dislocation tangles).Specifically,because of different dislocation morphologies,the magnetic field positively and negatively affects the dislocation activity in samples I and II,leading to enhanced and suppressed precipitation behaviors,***,nucleation of theηphase is facilitated in the UFG alloy at the critical temperature(140℃)because it affords a faster rate of atom diffusion and a higher dislocation density as compared to those exhibited by its coarse-grained *** systematic and comprehensive study provides new insights into dislocation morphology and precipitation behaviour of the UFG 7075 Al alloy,while enabling the optimization of precipitation kinetics.

关键词： Ultrafine-grained Al alloy Precipitation behaviors Magnetic field Dislocation morphology Critical temperature

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Precipitation behavior and grain refinement of burnishing Al-Zn-Mg alloy

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Progress in Natural Science:Materials International 2018年第1期28卷 54-59页

作者： Ce Pang hongyun luo Zheng Zhang Yue Ma Key Laboratory of Aerospace Materials and Performance School of Materials Science and Engineering Beihang University

Burnishing is a unique strengthening approach to improve the strength of surface layer and remains the ductility of the interior of metallic materials. In this work, burnishing treatment was employed to improve the surface microstructure of naturally aged Al-Zn-Mg alloys after solid solution. Transmission electron microscopy, highresolution transmission electron microscopy, X-ray diffraction and nano-indentation were used to characterize the effects of the burnishing on the microstructures of surface layer and Guinier-Preston(GP) zones. It was indicated that GP zones uniformly distributed and dispersed in the matrix before burnishing, and the amount of GP zones decreased dramatically after burnishing processing. Additionally, the grains in the surficial layer were refined into nano-crystals with an average grain size of 78 nm. Burnishing treatment not only led to formation of large number of dislocation substructures in the sub-surface and near-matrix surface, but also promoted the precipitation of metastable η' phase at grain boundaries. The synergistic effects of the grain refinement, dislocation multiplication and the precipitation of η' phase strengthen the burnished layer of Al-Zn-Mg alloy.

关键词： Al-Zn-Mg alloy Burnishing Nano-crystal Precipitation Grain refinement

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Characterization of Passive Films Formed on As-received and Sensitized AISI 304 Stainless Steel

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Chinese Journal of Mechanical Engineering 2019年第2期32卷 61-72页

作者： Yubo Zhang hongyun luo Qunpeng Zhong Honghui Yu Jinlong Lv Key Laboratory of Aerospace Materials and Performance (Ministry of Education) School of Materials Science and Engineering Beijing University of Aeronautics and Astronautics The Collaborative Innovation Center for Advanced Aero-Engine (CICAAE) Beijing University of Aeronautics and Astronautics Beijing Key Laboratory of Advanced Nuclear Materials and Physics Beijing University of Aeronautics and Astronautics China Waterborne Transport Research Institute Beijing Key Laboratory of Fine Ceramics Institute of Nuclear and New Energy Technology Tsinghua University

The current research of corrosion resistance of stainless steels mainly focuses on characterization of the passive films by point defect mode and mixed-conduction model. The corrosion resistance of the passive films formed on asreceived and sensitized AISI304 stainless steel in borate bu er solution were evaluated in this paper. The degree of sensitization and corrosion resistance of AISI304 stainless steels was evaluated by double loop electrochemical potentiodynamic reactivation and electrochemical impedance spectroscopy. The passive films formed on the stainless steels were studied by XPS technique. It was found that as-received specimen had higher pitting corrosion potential and corrosion resistance than sensitized one. The Mott-Schottky results showed that sensitized stainless steel had more defects in the passive film than as-received one. The compositions of the passive films were mainly Cr and Fe oxides according to XPS results.

关键词： 304 stainless steel Sensitization Passive films XPS Impedance

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The Probabilistic Safety Assessment of the Rail Mounted Gantry Cranes

The Probabilistic Safety Assessment of the Rail Mounted Gant...

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中国材料大会2012

作者： Yubo Zhang Yiqin Li hongyun luo School of Material Science and Engineering Beijing University of Aeronautics and Astronautics China Waterborne Transportation Institute

ISBN: (纸本)9783037856093

The technology of PSA（probabilistic safety assessment） based on fracture mechanics has been applied on the engineering field. However there’re few application on the port machines still with some problems. A comprehensive discuss on PSA method was presented in this paper. Firstly, the experiment of the fracture mechanics parameters of Q345 steel used on the port machine’s structures was made to provide the parameters for PSA. Secondly, probabilistic analysis with the series of the Q345 steel’s FAC（Failure Assessment Curve） provides the PSA criterion. By using stress analysis, defect detection and material properties, the structures safety of a RMG（Rail Mounted Gantry） of one port in service were assessed, the result show that the key points of the crane are safe in one point service. The technology presented in this paper will be significant for the operation and management of the port equipment.

关键词： Rail Mounted Gantry (RMG) Cranes Fracture toughness—KIC Probabilistic Safety Assessment (PSA) Probabilistic Failure Assessment Curve (PFAC)

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The Effect of Strain on the Impedance and Surface Potential of Austenite in 304 Stainless Steels

The Effect of Strain on the Impedance and Surface Potential ...

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中国材料大会2012

作者： Jinpeng Xi hongyun luo Jinlong Lv Key Laboratory of Aerospace Materials and Performance （Ministry of Education） School of Materials Science and Engineering Beihang University

ISBN: (纸本)9783037856093;3037856092

Local electrochemical technique was used to measure the impedance of austenite in AISI 304 stainless steel under tensile strain of 0%, 10%, 20%, 30%, 40%. Scanning Kelvin probe （SKP） technique was used to measure the potential distribution of the surface. The results showed that the impedance of the austenite declined with the increase of the strain and declined sharply under the strain of 30%. Potential of austenite decreased non-monotonously with increase of the strain. The potential reached the minimum under strain of 30% and then increased. Through the transmission electron microscope （TEM） results, plane dislocation pile-ups were observed in the grain boundary under the strain of 30% and transformed to cellular substructure structure and cell wall under 40%. Combined with the results of local electrochemistry impedance spectroscopy （LEIS） and surface potential, it may be concluded that it was the dislocation density and dislocation structure influence the impedance spectroscopy significantly, while surface potential was sensitive to the dislocation structure.

关键词： LEIS Surface potential Dislocation density

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Effects of Texture on Tensile Property of Extruded AZ31 Magnesium Alloy Investigated by Acoustic Emission

Effects of Texture on Tensile Property of Extruded AZ31 Magn...

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中国材料大会2012

作者： Chuankai Sun hongyun luo Zhiyuan Han Key Laboratory of Aerospace Materials and Performance （Ministry of Education） School of Materials Science and EngineeringBeihang University

ISBN: (纸本)9783037856086;3037856084

In this paper, effects of texture on tensile property of extruded AZ31 magnesium alloy are investigated by acoustic emission （AE）. The results show that the extruded AZ31 magnesium alloy used in this research has the strong texture of {1120}＜1010＞ and tensile anisotropy. The yield strength of TD-sample is about 80MPa, which is half of that of ED-sample. AE results show that the AE count of the TD-sample is higher than that of the ED-sample. These AE results suggest that there are more deformation twins in the TD-sample than in the ED-sample. It can be concluded that the deformation twinning can strongly influence the anisotropy, which is mainly due to the flow stress relief induced by twinning and the interaction of twins and dislocations during the strain hardening.

关键词： AZ31 magnesium alloy Texture Tensile property Acoustic emission

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强制性制度变迁中的路径依赖问题研究——以建国初期土地改革为例

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开发研究 2011年第2期 88-91页

作者：罗红云新疆财经大学公共经济与管理学院新疆乌鲁木齐830012

本文通过对中国农地制度的历史考察,认为传统平均主义和个人主义意识对农民行为选择的影响是促使中共中央在建国初继续土地改革建立农民土地所有制的思想渊源。从土地改革的制度内涵以及传统中国和中国共产党在民主革命时期土地制度变... 详细信息

本文通过对中国农地制度的历史考察,认为传统平均主义和个人主义意识对农民行为选择的影响是促使中共中央在建国初继续土地改革建立农民土地所有制的思想渊源。从土地改革的制度内涵以及传统中国和中国共产党在民主革命时期土地制度变革的历史来看,土地改革建立的农民土地所有制是呈现明显路径依赖特性的连续的强制性制度变迁。

关键词：土地改革农民土地所有制路径依赖制度变迁

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在役钢结构概率安全评定方法

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北京航空航天大学学报 2005年第8期31卷 925-929页

作者：骆红云钟群鹏张峥北京航空航天大学材料科学与工程学院北京100083

针对大型在役钢结构的安全评定问题,综合利用第二水平法和MonteCarlo法,提出了静载和疲劳条件下概率安全评定的方法;并利用三阶段腐蚀规律对海洋气候腐蚀条件下概率安全评定过程进行了修正.以青岛港装船机主梁和翻车机端环为例进行了实... 详细信息

针对大型在役钢结构的安全评定问题,综合利用第二水平法和MonteCarlo法,提出了静载和疲劳条件下概率安全评定的方法;并利用三阶段腐蚀规律对海洋气候腐蚀条件下概率安全评定过程进行了修正.以青岛港装船机主梁和翻车机端环为例进行了实际结构的安全评定分析计算,分别得出了这些结构中一些缺陷的确定性和概率安全评定结果.2种评定结果是大体上是相近的,但也存在一些不同.通过对这些确定性和概率安全评定结果的对比分析,得到了确定性和概率性安全评定方法的初步关系式—近似为单对数线性关系,此结论为概率安全评定方法的工程化奠定了基础.

关键词：概率安全评定钢结构疲劳腐蚀

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中国绿色创新效率空间关联网络特征及其驱动因素研究

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生态经济 2024年第7期40卷 57-65页

作者：王东罗红云新疆财经大学财政税务学院新疆乌鲁木齐830012

运用基于序列DEA的SE-U-SBM模型测度我国30个省份2007—2019年绿色创新效率,利用修正的引力模型和社会网络分析方法解构了我国省际绿色创新效率的空间关联特征,并借助QAP方法探讨了绿色创新效率空间关联网络的驱动因素。研究结果显示:(1... 详细信息

运用基于序列DEA的SE-U-SBM模型测度我国30个省份2007—2019年绿色创新效率,利用修正的引力模型和社会网络分析方法解构了我国省际绿色创新效率的空间关联特征,并借助QAP方法探讨了绿色创新效率空间关联网络的驱动因素。研究结果显示:(1)我国省际绿色创新效率上升趋势明显,呈现东部>中部>西部的空间分布格局。(2)中国绿色创新效率的空间关联呈现出复杂的多线程空间网络关联关系,省际绿色创新效率的关联性不断加强,空间关联网络稳定性进一步增强,东部省份大多属于净溢出板块,中西部省份为相对受益板块。(3)地理距离、城镇化水平差异、人力资本差异、财政分权差异、相近的R&D投入强度和资源禀赋差异是影响我国绿色创新效率空间关联网络形成与发展的重要驱动因素,对绿色创新效率空间关联网络具有显著的促进作用。应着力推动要素市场化改革,破除区域市场分割和行政壁垒,加强区域政策协调性,实现绿色创新效率协同提升。

关键词：绿色创新效率社会网络分析 QAP方法驱动因素

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国产压力容器用钢的概率失效评定曲线

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北京航空航天大学学报 2006年第4期32卷 450-454页

作者：骆红云张玉波钟群鹏北京航空航天大学材料科学与工程学院北京100083 长春工业大学机电工程学院长春130012

随着概率安全评定技术(PSA,Probabilistic Safety Assessment)的发展,该技术已经开始逐步向工程应用领域渗透,但其在应用方面还存在若干的问题,失效评定曲线的概率化就是其主要问题之一.对多个厂家、多种炉号、多种板厚4种国产钢种5种... 详细信息

随着概率安全评定技术(PSA,Probabilistic Safety Assessment)的发展,该技术已经开始逐步向工程应用领域渗透,但其在应用方面还存在若干的问题,失效评定曲线的概率化就是其主要问题之一.对多个厂家、多种炉号、多种板厚4种国产钢种5种裂纹形式的大量失效评定曲线进行了概率分析,采用三段分析法和逼近法得到了不同可靠度下的4种国产钢的概率失效评定曲线及其表达式,以及一般长屈服平台国产钢在不同可靠度下的一般失效评定曲线及其表达式.运用这些表达式可实现适合我国国产钢种含缺陷构件的工程概率安全评定分析.

关键词：概率安全评定概率失效评定曲线国产压力容器用钢

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