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Effect of alloying elements and processing parameters on the Portevin–Le Chatelier effect of Al–Mg alloys

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International Journal of Minerals,Metallurgy and Materials 2015年第2期22卷 175-183页

作者： Peng-cheng Ma Di Zhang Lin-zhong zhuang Ji-shan Zhang State Key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing

The effects of alloying elements and processing parameters on the mechanical properties and Portevin-Le Chatelier effect of A1-Mg alloys developed for inner auto body sheets were investigated in detail. Tensile testing was performed in various Zn and Mg contents under different annealing and cold-rolling conditions. In the results, the stress drop and reloading time of serrations increase with increasing plastic strain and exhibit a common linear relationship. The increase rates of stress drop and reloading time increase with increasing Mg or Zn content. The alloys with a greater intensity of serrated yielding generally exhibit a greater elongation. The stress drop and reloading time of serrations decrease with increasing grain size in the case of the annealed samples. The cold-rolled sample exhibits the most severe serra- tion because it initially contains a large number of grain boundaries and dislocations.

关键词： aluminum-magnesium alloys Portevin-Le Chatelier effect alloying elements processing parameters mechanical properties

Twinning Behavior of a Basal Textured Commercially Pure Titanium Alloy TA2 at Ambient and Cryogenic Temperatures

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Journal of Iron and Steel Research International 2016年第1期23卷 74-77页

作者： Jin-ru LUO Xiao SONG Lin-zhong zhuang Ji-shan ZHANG State Key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing

Twinning greatly affects the microstructure and mechanical performance of titanium *** twinning behavior of a basal textured commercially pure titanium TA2 plates rolled to 4% reduction at the ambient and cryogenic temperatures has been *** of the rolled samples were investigated by optical microscope（OM）and the twinning analysis was carried out based on orientation data collected by electron back-scatter diffraction（EBSD）.{1122}contraction twins,{1124}contraction twins and {1012}extension twins have been *** mode activity varied with rolling *** is considered as the dominant deformation mechanism during rolling at both temperatures for the strain *** proportion of grains activates twinning during cryorolling,and greater number and more diverse types of twins are observed;manifestly related to the suppression of dislocation slips at the cryogenic temperature.{1122}contraction twins are the dominate twin type within samples rolled at both ***{1124}contraction twins are observed in the cryorolled sample while there are only a few in the sample rolled at room temperature.A few tiny{1012}twins have been identified in both samples.{1124}contraction twins are preferentially activated at cryogenic deformation temperature and the{1012}extension twins may result in local strain accommodation.

关键词： titanium rolling twinning cryogenic temperature

Phase Transition and Oxygen Ion Diffusion in （La1-xLnx）2Mo2O9 （Ln=Nd, Gd, x=0.05-0.25） Using Dielectric Relaxation Method

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Chinese Journal of Chemical Physics 2008年第3期21卷 270-274页

作者： Qian-feng Fang zhong zhuang Xian-ping Wang Dan Li Jian-xin Wang Ningbo Institute of Material Technology and Engineering Chinese Academy of Sciences Ningbo315040 China Key Laboratory of Materials Physics Institute of Solid State Physics Chinese Academy of SciencesHefei 230031 China

Dielectric relaxation method was employed to study the properties of oxygen ion diffusion and phase transition in the oxide-ion conductors （Lal-xLnx）2Mo209 （Ln=Nd, Gd, x=0.05-0.25）. Two dielectric loss peaks were observed： peak Pd at about 600 K and peak P5 around 720 K. Peak Pd is a relaxational peak and associated with the short-range diffusion of oxygen ions, while peak P5 hardly changes its position and dramatically decreases in height with increasing frequency, exhibiting non-relaxational nature. With increasing Ln^3＋ concentration, the heights of peak Ph and Pd increase at first and then decrease after passing a maximum at 15% doping. It is suggested that peak P5 is related to the phase transition of a static disordered state to a dynamic disordered state in oxygen ions/vacancies distribution. It is found that the 15%Gd or 15%Nd doped La2Mo209 samples exhibit the highest conductivity in accordance with the highest height of peak Pd at this doping content.

关键词： Oxide-ion conductor La2Mo2O9 Dielectric relaxation Oxygen ion diffusion

Microstructure and mechanical properties of cryorolled AZ31 magnesium alloy sheets with different initial textures

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International Journal of Minerals,Metallurgy and Materials 2016年第7期23卷 827-834页

作者： Jin-ru Luo Ya-qiong Yan Ji-shan Zhang Lin-zhong zhuang State Key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing

AZ31 magnesium alloy sheets with different strong textures were cryorolled at the liquid-nitrogen temperature to the strain of 4% and 8%. The microstructure and texture of the rolled sheets were investigated via scanning electron microscopy（SEM）, electron backscatter diffraction（EBSD）, and X-ray diffraction（XRD）. The mechanical properties of the sheets were tested through in-plane uniaxial tensile tests at ambient temperature. The tensile stress was exerted in the rolling direction（RD） and transverse directions（TD）. The microstructural and textural evolutions of the alloy during cryorolling were investigated. Due to active twining during rolling, the initial texture significantly influenced the microstructural and textural evolutions of the rolled sheets. A {10 12} extension twin was found as the dominated twin-type in the cryorolled samples. After cryogenic rolling, the ductility of the samples decreased while the strength increased. Twinning also played an important role in explaining the mechanical differences between the rolled samples with different initial textures. The samples were significantly strengthened by the high stored energy accumulated from cryorolling.

关键词： magnesium alloy cryorolling microstructure mechanical properties twinning

Microstructure characterization in a sensitized Al-Mg-Mn-Zn alloy

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Rare Metals 2018年第2期37卷 129-135页

作者： Chun-Yan Meng Di Zhang Ping-Ping Liu Lin-zhong zhuang Ji-Shan Zhang State Key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing School of Materials Science and Engineering University of Science and Technology Beijing

Alloying elements, present in the aluminum solid solution or the precipitates, influence the corrosion resistance of A1-Mg-Mn-Zn alloys. In this study, sensi- tizing treatment was applied to an A1-Mg-Mn-Zn alloy to modify the precipitation at the grain boundaries or in the grains. Transmission electron microscopy （TEM） and scanning electron microscope （SEM） were used to characterize various second-phase particles and determine their orientation relationship with the A1 matrix. After sensitizing treatment, z-phase （Mg32（Al, Zn）49） is observed to precipitate along the grain boundaries in a coarser size, producing a discontinuous grain boundary precipitate structure. In addition, Mn-rich particles are found to form with various shapes, such as global, plate and rhombus.

关键词： Al-Mg-Mn-Zn alloy Mg32(A1, Zn)49 phase A16(Mn, Fe) phase Microstructure characterization

Mechanical properties and constitutive behaviors of as-cast 7050 aluminum alloy from room temperature to above the solidus temperature

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International Journal of Minerals,Metallurgy and Materials 2016年第8期23卷 949-958页

作者： Qing-ling Bai Hong-xiang Li Qiang Du Ji-shan Zhang Lin-zhong zhuang State Key Laboratory for Advanced Metals and Materials University of Science and Technology BeijingBeijing 100083China SINTEF Materials and Chemistry TrondheimNorway

The mechanical properties and constitutive behaviors of as-cast AA7050 in both the solid and semi-solid states were determined using the on-cooling and in situ solidification approaches, respectively. The results show that the strength in the solid state tends to increase with decreasing temperature. The strain rate plays an important role in the stress–strain behaviors at higher temperatures, whereas the influence becomes less pronounced and irregular when the temperature is less than 250°C. The experimental data were fitted to the extended Ludwik equation, which is suitable to describe the mechanical behavior of the materials in the as-cast state. In the semi-solid state, both the strength and ductility of the alloy are high near the solidus temperature and decrease drastically with decreasing solid fraction. As the solid fraction is less than 0.97, the maximum strength only slightly decreases, whereas the post-peak ductility begins to increase. The experimental data were fitted to the modified creep law, which is used to describe the mechanical behavior of semi-solid materials, to determine the equivalent parameter fGBWL, i.e., the fraction of grain boundaries covered by liquid phase.

关键词： aluminum alloys mechanical properties constitutive relations fitting

Effect of cryogenic rolling and annealing on the microstructure evolution and mechanical properties of 304 stainless steel

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International Journal of Minerals,Metallurgy and Materials 2017年第6期24卷 638-645页

作者： Jin-tao Shi Long-gang Hou Jin-rong Zuo Lin-zhong zhuang Ji-shan Zhang State Key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing Beijing 100083 China

Metastable 304 austenitic stainless steel was subjected to rolling at cryogenic and room temperatures, followed by annealing at different temperatures from 500 to 950°C. Phase transition during annealing was studied using X-ray diffractometry. Transmission electron microscopy and electron backscattered diffraction were used to characterize the martensite transformation and the distribution of austenite grain size after annealing. The recrystallization mechanism during cryogenic rolling was a reversal of martensite into austenite and austenite growth. Cryogenic rolling followed by annealing refined grains to 4.7 μm compared with 8.7 μm achieved under room-temperature rolling, as shown by the electron backscattered diffraction images. Tensile tests showed significantly improved mechanical properties after cryogenic rolling as the yield strength was enhanced by 47% compared with room-temperature rolling.

关键词： stainless steel cryogenic rolling annealing microstructural evolution mechanical properties recrystallization

The First Generation of New China Leaders' Thought of Developing Integrated Chinese and Western Medicine

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Chinese Journal of Integrative Medicine 2018年第5期24卷 385-389页

作者： WENG Pan-feng1 LI En-chang1 zhuang Xing-zhong2 Health and Life Ethics Center Wenzhou Medical University Department of Organizational Work Wenzhou Medical University

The history of integrated Chinese medicine （CM） and Western medicine （WM） witnesses the development of public health under the significant support and guidance of the first generation leaders of new China who aimed at maximizing people＇s health interests. According to the available documents, it can be found out that, among the first generation of new China leaders, MAO Ze-dong, ZHOU En-lai, LIU Shao-qi, ZHU De and DENG Xiao-ping made more statements on the integration of CM and WM due to different division of labor and other historical reasons. This paper will focus on the issue to study the emergence, formation and development of their thoughts on the integration of CM and WM and analyze its process and significance, so as to enlighten the current integration of CM and WM, and even the world＇s integrative medicine.

关键词： In De Thought of Developing Integrated Chinese and Western Medicine The First Generation of New China Leaders WM

Electrical properties of garnet-like lithium ionic conductors Li5＋xSrxLa3-xBi2O12 fabricated by spark plasma sintering method

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Frontiers of Materials Science 2012年第3期6卷 216-224页

作者： Yun-Xia GAO Xian-Ping WANG Qin-Xing SUN zhong zhuang Qian-Feng FANG Key Laboratory of Materials Physics Institute of Solid State PhysicsChinese Academy of SciencesHefei 230031China

A typical approach involving Pechini method and spark plasma sintering （SPS） method was presented for the preparation of high density Li5＋xSrxLa3_xBi2012 （x = 0, 1） ceramics. Phase formation, microstructure, grain size and electrical properties of the specimens were examined using XRD, SEM and alternating current impedance spectro- scopy （ACIS）. Dense LisLa3Bi2012 and LisSrLa2Bi2012 ceramics with pure garnet-like phase, relative density of 97% and average grain size of about 5 pm were fabricated using this approach. The total conductivities at 298 K of Li5La3Bi2012 and LisSrLa2Bi2O12 ceramics prepared by the SPS method are 5.1 Qian-Feng FANG105 and 6.810SS/cm, respectively, 2 times higher than that of samples prepared by the conventional sintering method.

关键词： lithium ionic conductor Lis.xSrxLa3_xBi2012 Pechini method spark plasmasintering (SPS) ionic conductivity