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Hot compressive deformation behaviors of Mg–10Gd–3Y–0.5Zr alloy

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Progress in Natural Science:Materials International 2016年第1期26卷 78-84页

作者： Tingting Zheng Dejiang Li xiaoqin zeng Wenjiang Ding National Engineering Research Center of Light Alloy Net Forming School of Materials Science and Engineering Shanghai Jiao Tong University

In this paper, the hot compressive deformation characteristics of a Mg–10Gd–3Y–0.5Zr（GW103K） alloy have been investigated by isothermal compression test at the temperature range of 350–450°C and strain rate range of 0.0001–0.1s-1. True stress–strain relationships at various strain rates showed the typical strain hardening and softening stage which is indicative of dynamic recrystallization during deformation. The results showed that the peak stress was obviously dependent on temperature and strain rate. A constitutive equation to describe the deformation process was established based on the hyperbolic sine function. The stress exponent n and apparent activation energy Q were determined to be 3.018 and 203.947 k J/mol, respectively. Microstructure investigation showed that dislocation slipping was the dominant deformation mechanism during the hot deformation at all conditions. However, at the temperatures lower than 400 °C and strain rates higher than 0.01 s-1, twinning was observed to be activated, which indicated another deformation mechanism. Dynamic recrystallization and dynamic precipitation were found to occur simultaneously under such deformation condition.

关键词： Mg-RE alloys Hot deformation Dynamic precipitation Constitutive equation Microstructure evolution

Investigation of the alloying effect on deformation behavior in Mg by Visco-Plastic Self-Consistent modeling

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Journal of Magnesium and Alloys 2020年第1期8卷 210-218页

作者： Alireza Maldar Leyun Wang Gaoming Zhu xiaoqin zeng National Engineering Research Center of Light Alloy Net Forming School of Materials Science and EngineeringShanghai Jiao Tong UniversityShanghai 200240China The State Key Laboratory of Metal Matrix Composites Shanghai Jiao Tong UniversityShanghai 200240China

Alloying elements can drastically alter the deformation behavior of *** the present work,Visco-Plastic Self-Consistent(VPSC)modeling was employed to investigate the effect of alloying elements on Mg’s tensile behavior,in particular the relative activity of different slip and twinning ***-0.47 wt.%Ca,Mg-2 wt.%Nd,and AZ31 extruded alloys were deformed by micro-tensile tests in a scanning electron microscope(SEM).Texture and grain size measured by electron backscatter diffraction(EBSD)were used as the input for *** parameter optimization,the VPSC model successfully reproduced the stress-strain curve of each *** results indicate that the slip/twinning activity in the three alloys are ***-0.47 wt.%Ca shows strong extrusion texture,and prismatic slip was quite active during its tensile *** contrast,Mg-2 wt.%Nd shows weak extrusion texture,and basal slip was *** alloy also developed more twinning activity than the other two ***31 shows strong extrusion texture similar as Mg-0.47 wt.%Ca,but prismatic slip was less active in *** slip/twinning activity revealed by the VPSC model can explain the difference in the tensile behavior of the three alloys.

关键词： Mg alloys Crystal plasticity Slip EBSD Tensile test

Grain-scale deformation in a Mg-0.8wt% Y alloy using crystal plasticity finite element method

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Journal of Materials Science & Technology 2019年第10期35卷 2200-2206页

作者： Wenxue Li Leyun Wang Bijin Zhou Chuanlai Liu xiaoqin zeng National Engineering Research Center of Light Alloy Net Forming School of Materials Science and EngineeringShanghai Jiao Tong UniversityShanghai200240China The State Key Laboratory of Metal Matrix Composites Shanghai Jiao Tong UniversityShanghai200240China

Magnesium(Mg) alloys with hexagonal close-packed(HCP) structure usually have a poor ductility at room temperature. The addition of yttrium(Y) can improve the ductility of Mg alloys. To understand the underlying mechanism, crystal plasticity finite element method(CPFEM) was employed to simulate the tensile deformation of a Mg-0.8 wt% Y alloy. The simulated stress–strain curve and the grain-scale slip activities were compared with an in-situ tensile test conducted in a scanning electron *** to the CPFEM result, basal slip is the dominant deformation mode in the plastic deformation stage, accounting for about 50% of total strain. Prismatic slip and pyramidal a slip are responsible for about 25% and 20% of the total strain, respectively. Pyramidal c + a slip and twinning, on the other hand,accommodate much less strain.

关键词： Magnesium alloys Crystal Plasticity finite element modeling EBSD Dislocation Mechanical Behavior

Designing strategy for corrosion-resistant Mg alloys based on film-free and film-covered models

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Journal of Magnesium and Alloys 2023年第9期11卷 3120-3129页

作者： Pengyu Zhao Tao Ying Fuyong Cao xiaoqin zeng Wenjiang Ding National Engineering Research Center of Light Alloys Shanghai Jiao Tong UniversityShanghai 200240PR China Center for Marine Materials Corrosion and Protection College of MaterialsXiamen University361005PR China

Mathematical models were proposed to clarify the effect of alloying on corrosion of magnesium alloys based on film-free and film-covered status. The models are applicable to explain the “barrier effect” by cathodes and the “analogous Hall-Petch relationship” between corrosion rates and grain size. The slope of corrosion rates versus alloying content is determined by the dissolution ability of film-free substrate and the hindering effects by corrosion product film. Designing strategy for corrosion-resistant Mg alloys is established.

关键词： Magnesium Corrosion Modeling Electrochemistry

Adaptive Cockroach Colony Optimization for Rod-Like Robot Navigation

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Journal of Bionic Engineering 2015年第2期12卷 324-337页

作者： Le Cheng Lixin Han xiaoqin zeng Yuetang Bian Hong Yan College of Computer and Information Hohai University Nanjing 210098 China Department of Computer Science and Engineering Huaian College of Information Technology China School of Business Nanjing Normal University Nanjing 210023 China School of Electrical and Information Engineering University of Sydney NSW 2006 Australia ~ Department of Electronic Engineering City University ofHong Kong Tat Chee Avenue Kowloon Hong Kong China

Based on the Cockroach Swarm Optimization （CSO） algorithm, a new Cockroach Colony Optimization （CCO） algorithm is presented and applied to the Robot Path Planning （RPP） problem in this paper. In the CCO algorithm, an improved grid map is used for environment modeling, and 16-geometry and 8-geometry are introduced, respectively, in food division and cockroach search operation. Moreover, the CCO algorithm adopts a non-probabilistic search strategy, which avoids a lot of invalid searches. Furthermore, by introducing a novel rotation scheme in the above CCO algorithm, an Adaptive Cockroach Colony Optimization （ACCO） algorithm is presented for the 2-D Rod-Like Robot Path Planning （RLRPP） problem. The simulation results show that the CCO algorithm can plan an optimal or approximately optimal collision-free path with linear time com- plexities. With the ACCO algorithm, the robot can accomplish intelligent and adaptive rotations to avoid obstacles and pass through narrow passages along the better path.

关键词： CCO robot path planning adaptive CCO rod-like robot path planning piano mover's problem

A hot tearing criterion based on solidifcation microstructure in cast alloys

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Journal of Materials Science & Technology 2022年第10期105卷 68-80页

作者： Bo Hu Zixin Li Dejiang Li Tao Ying xiaoqin zeng Wenjiang Ding National Engineering Research Center of Light Alloy Net Forming School of Materials Science and EngineeringShanghai Jiao Tong UniversityShanghai 200240China The State Key Laboratory of Metal Matrix Composites Shanghai Jiao Tong UniversityShanghai 200240China

A criterion based on solidifcation microstructure was proposed to precisely predict the hot tearing behavior of cast alloys,which takes into account the effects of both mechanical and nonmechanical *** criterion focuses on the events occurring at the grain boundary,which are determined by the thermal contraction,solidifcation shrinkage,grain growing and liquid *** criterion responds to a series of factors that affect hot tearing,such as alloy composition,mold design,casting process and *** credibility has been validated by studying the hot tearing behavior of Mg-Ce *** conformity with the experimental results,this criterion predicted decrease in the number of rods occurring hot tearing with increasing cerium content.A simplifed criterion was derived and validated by Mg-Ce(equiaxed grain)and Mg-Al(columnar grain)alloy systems,which is suitable for the case where the eutectic liquid fraction is low and the liquid feeding can be *** addition,a hot tearing index for equiaxed grains was proposed,that is,|d T/d(f_(s)^(1/3)near(f_(s))^(1/3)=1,and its prediction results were consistent with the hot tearing susceptibility calculated from the experimental results.

关键词： Hot tearing Microstructure Magnesium alloys Casting Criterion

Phase equilibria of long-period stacking ordered phase in the ternary Mg-Y-Al alloys

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Journal of Materials Science & Technology 2022年第31期126卷 80-92页

作者： Yiwen Chen Quan Li Yangxin Li Weisen Zheng Jingya Wang xiaoqin zeng National Engineering Research Center of Light Alloy Net Forming Shanghai Jiao Tong UniversityShanghai 200240China State Key Laboratory of Metal Matrix Composites Shanghai Jiao Tong UniversityShanghai 200240China State Key Laboratory of Advanced Special Steels School of Materials Science and EngineeringShanghai UniversityShanghai 200444China

Phase equilibria focusing on the long-period stacking ordered(LPSO)phases have been experimentally in-vestigated in the Mg-Y-Al *** microstructures of the eleven representative alloys annealed at 450,500 and 550°C were systematically investigated using X-ray diffraction(XRD),scanning electron mi-croscopy(SEM)and transmission electron microscopy(TEM).Two thermodynamically stable LPSO poly-types were identified,including 18R and 10H ***,the transformation of 18R→10H was detected in Mg-9.0Y-1.7Al(at.%)alloy,while the coexistence of 18R and 10H was observed in Mg-14.2Y-12.8Al(at.%)*** was found that the LPSO phases were non-stoichiometric compounds with ternary *** 18R can dissolve up to 7.21 at.%-8.37 at.%Al and 10.75 at.%-12.01 at.%Y,while the 10H can dissolve up to 9.35 at.%-10.37 at.%Al and 14.50 at.%-14.94 at.%*** of the experimental re-sults were used to construct the isothermal sections,which is conducive to the design of Mg-Y-Al alloys.

关键词： Mg-Y-Al alloys LPSO phases Phase relationships Isothermal sections Atomic structure

High-resolution characterization of the fretting corrosion of Alloy 690 in the simulated secondary water of pressurized water reactor

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Journal of Materials Science & Technology 2023年第20期151卷 30-40页

作者： You Wang Zhangjian Zhou Hui Wang Jiang Ju Zhao Shen xiaoqin zeng School of Materials Science and Engineering University of Science and Technology BeijingBeijing 100083China Interdisciplinary Materials Research Center Institute for Advanced StudyChengdu UniversityChengdu 610041China School of Materials Science and Engineering Shanghai Jiao Tong UniversityNo.800 Dongchuan RoadShanghai 200240China

The worn scars on Alloy 690 after the fretting corrosion testing in simulated pressurized water reactor(PWR)secondary water have been comprehensively analyzed by scanning transmission electron microscopy(STEM)and transmission Kikuchi diffraction(TKD).The high-quality characterization results experimentally show that the fretting wear accelerates the corrosion of Alloy 690 in two *** first one is to break the integrity of the oxide scale by introducing cavities at the oxide grain *** second one is to alter the microstructure of the underneath matrix,forming a nano-grained matrix *** increased grain boundary density in this layer can accelerate the consumption of Cr in the near-surface *** loss of oxide scale integrity and the accelerated Cr consumption are believed to contribute to the deteriorated corrosion resistance of Alloy 690 during the fretting corrosion process.

关键词： Alloy 690 Corrosion Fretting wear Transmission electron microscopy Transmission Kikuchi Diffraction

Dominant Deformation Mechanisms in Mg–Zn–Ca Alloy

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Acta Metallurgica Sinica(English Letters) 2022年第12期35卷 1973-1982页

作者： Tao Ying Mingdi Yu Yiwen Chen Huan Zhang Jingya Wang xiaoqin zeng National Engineering Research Center of Light Alloy Net Forming and State Key Laboratory of Metal Matrix Composites Shanghai Jiao Tong UniversityShanghai 200240China

The coaddition of Zn and Ca has great potential to improve the ductility of Mg ***,the mechanical properties of an extruded Mg-Zn-Ca solid-solution alloy were studied by quasi-in situ electron backscatter diffraction(EBSD)-assisted slip trace *** dominant deformation mechanisms of the Mg-Zn-Ca alloy were studied,and the origins of enhanced ductility were systematically *** results indicate that most grains deformed by basal *** addition,multiple non-bas al slip traces were detected(particularly prismatic,pyramidal I,and pyramidal Islip traces),and their activation frequency was promoted with increasing tensile *** enhanced participation of non-basal slip systems is believed to play a critical role in achieving homogeneous plastic deformation,thus effectively promoting the ductility of the Mg-Zn-Ca ***,first-principle calculations revealed that the coaddition of Zn and Ca significantly reduces the unstable stacking fault energy for non-basal slip,which contributes to the activation of non-basal slip systems during plastic deformation.

关键词： Mg-Zn-Ca alloy Non-basal slip activities First-principle calculations Generalized stacking fault energy Deformation mechanisms