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Microstructure and texture optimization by static recrystallization originating from {10-12} extension twins in a Mg-Gd-Y alloy

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Journal of Materials Science & technology 2020年第24期59卷 44-60页

作者： S.H.Lu d.Wu r.S.Chen En-hou Han The group of Magnesium Alloys and Their Applications Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China

during the deformation of Mg alloys,{10-12}extension twin often contributes to the formation of basal texture but rarely assists the nucleation of recrystallization,i.e.,effective grain refinement,therefore it seems to make against the improvement of formability and mechanical *** this work,{10-12}extension twin has been creatively utilized as a preference nucleation site for static recrystallization(SrX),achieving grain refinement and orientation randomization in a Mg-Gd-Y alloy using multi-directional impact forging(MdIF)and subsequent annealing *** of{10-12}extension twin on SrX behavior has been investigated by annealing treatment at 450℃using quasi-in-situ optical microscopy(OM)and quasi-in-situ electron back-scattering diffraction(EBSd).The microstructural evolution during annealing shows that several SrX gains can nucleate from the grain boundary of untwinned grains,but they only have few influences on the final microstructure due to their limited volume faction and sluggish *** contrast,a large number of SrX gains can initiate from{10-12}extension twin and grow up without the confine of twin ***,they consume their parent grains and make the main contribution to grain *** should be attributed to those pinned{10-12}twin boundary,by interacting with various dislocation slips during the MdIF process,which can operate like grain boundary,store enough strain energy,and promote the nucleation of SrX during *** the other hand,SrX grains usually keep initial random orientation and further randomize the forging texture during annealing treatment.

关键词： Mg-Gd-Y alloy Multi-directional impact forging(MdIF) {10-12}extension twin Quasi-in-situ electron back-scattering diffraction(EBSd) Static recrystallization(SrX)

Enhanced tensile properties in a Mg-6Gd-3Y-0.5Zr alloy due to hot isostatic pressing(HIP)

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Journal of Materials Science & technology 2019年第9期35卷 1860-1868页

作者： B. Zhoua d.Wu r.S.Chen En-hou Han The group of Magnesium Alloys and Their applications Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaHefei 230026China

Hot isostatic pressing (HIP) was applied to Mg-6Gd-3Y-0.5Zr (GW63) alloy to reduce shrinkage porosity, thus, to enhance the integrity and reliability of castings. during HIP process, shrinkage porosity was closed by grain compatible deformation and subsequent diffusion across the bonding interface. The amount of initial shrinkage porosity was the key factor for shrinkage porosity closure. HIP was testified to be effective on shrinkage porosity reduction in GW63 alloy due to its relatively narrow solidification range and resultant low content of initial shrinkage porosity in most sections, leading to higher tensile properties both in as-cast and cast-T6 condition. The improvement in tensile properties was mainly because of shrinkage porosity reduction and resultant effective rare-earth (rE) elements homogenization and precipitation strengthening.

关键词： Hot isostatic pressing Mg-Gd-Y-Zr Shrinkage porosity reduction Tensile properties

New method of improving parts accuracy by adding heat balance support in selective laser sintering

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2009年第3期10卷 361-369页

作者： Bing LIU Li-chao ZHANG Jian-hua MO Bo QIAN State Key Laboratory of Plastic forming Simulation and die and Mould technology School of Material Science and Engineering Huazhong University of Science and Technology Wuhan 430074 China

In order to improve parts accuracy, a method of adding heat balance support （HBS） was proposed, and the detailed algorithm for generating HBS was developed. A number of experiments and a comparison between similar softwares, showed that the algorithm is efficient and feasible. Moreover, different features of riBS were studied for different kinds of materials, such as PS and nylon. The research findings indicate that automatically adding HBS can significantly improve the accuracy of the parts, and that the algorithm for generating HBS is efficient and precise.

关键词： Selective laser sintering (SLS) Accuracy Heat balance support (HBS) Triangular facet 3d rings

Effect of solute atom concentration and precipitates on serrated flow in Mg-3Nd-Zn alloy

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Journal of Materials Science & technology 2018年第7期34卷 1236-1242页

作者： W.H.Wang d.Wu r.S.Chen X.N.Zhang State Key Laboratory of metal Matrix Composites School of Materials Science and Engineering Shanghai Jiao Tong University The group of Magnesium Alloys and Their Applications Institute of Metal Research Chinese Academy of Sciences

Influence of solute atom concentration and precipitates on serrated flow, i.e., Portevin-Le Chatelier effect, was studied in Mg-3Nd-Zn alloy by tensile test at 250℃ with a strain rate of l x 10^-3 s^-1 Microstructure and tensile property of the Mg-3Nd-Zn alloy in solution and aging conditions were also investigated. results indicate that the serrated flow was weakened with aging time, and geometry of the serrations changed from sharp to rounded corner. Through analyzing the mechanism of the interactions between dislocations and solute atoms, it was identified that the precipitates did not only weaken the serrated flow due to the decrease in the concentration of solute atom, but also regulate the serration type by restraining the movement of dislocations during high temperature deformation.2017 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science ＆ technology.

关键词： Magnesium alloy Serrated flow Precipitate Heat treatment deformation behavior

dynamic microstructure evolution and mechanical properties of dilute Mg-Al-Ca-Mn alloy during hot rolling

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Journal of Materials Science & technology 2022年第34期129卷 1-14页

作者： Shiwei Xu Congcong Zhu Zhanhong Lin Chen Jin S.Kamado K.Oh-ishi Yun Qin College of Materials Science and Engineering Hunan UniversityChangsha 410082China State Key Laboratory of Advanced design and Manufacturing for Vehicle Body Hunan UniversityChangsha 410082China Qinghai Salt Lake Teli Magnesium Co.Ltd. Xining 810000China department of Mechanical Engineering Nagaoka University of TechnologyNagaoka 940-2188Japan Toyota Central r&d Labs. Inc.41-1 YokomichiNagakuteAichi 480-1192Japan research Institute(r&d Centre) Baowu Steel Group CorporationShanghai 201900China

The dynamic microstructure and texture of dilute Mg-0.50Al-0.71Ca-0.33Mn(wt.%) during hot rolling at two slab temperatures were investigated by electron backscattered diffraction(EBSd) and high resolution transmission electron microscopy(HrTEM). The results show that the development of the rolling microstructures is to first form {10–12} extension twins in the original grains, thereby forming the extension-twinned regions, and then to further form {10–11}-{10–12} double twins and kinks in the extension-twinned regions, and finally to form continuous dynamic recrystallized(continuous drXed)grains in the double twins and the cross parts of the shear-deformed coarse extension-twinned *** extension twins, double twins and kinks show a decisive effect on the formation of rolling *** number of {10–11}-{10–12} double twins and resultant the continuous drX process are strongly affected by the rolling slab temperature and the reduction thickness per pass. By optimizing the rolling conditions, texture and microstructures of the multi-pass rolled Mg-Al-Ca-Mn alloy sheets are successfully modified. Although the total alloy content is only 1.5 wt.%, these Mg-Al-Ca-Mn alloy sheets show much higher strength than the commercial Mg-3Al-1 Zn(wt.%)(AZ31B) sheet.

关键词： Mg-Al-Ca-Mn alloy Hot rolling dynamic recrystallization Texture control Mechanical properties

Combined Cellular Automaton Model for dynamic recrystallization Evolution of 42CrMo Cast Steel

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Chinese Journal of Mechanical Engineering 2018年第5期31卷 80-90页

作者： Yi-Na Guo Yong-Tang Li Wen-Yan Tian Hui-Ping Qi Hong-Hong Yan School of Electronic Information Engineering Taiyuan University of Science and Technology Shanxi Key Laboratory of metallic Materials forming Theory and technology School of Materials Science and Engineering Taiyuan University of Science and Technology

The dynamic recrystallization(drX) simulation performance largely depends on simulated grain topological struc?tures. However, currently solutions used di erent models for describing two?dimensional(2 d) and three?dimensional(3 d) grain size distributions. Therefore, it is necessary to develop a more universal simulation technique. A cellular automaton(CA) model combined with an optimized topology deformation technology is proposed to simulate the microstructural evolution of 42 CrMo cast steel during drX. In order to obtain values of material constants adopted in the CA model, hot deformation characteristics of 42 CrMo cast steel are investigated by hot compression metal?lographic testing. The proposed CA model deviates in two important aspects from the regular CA model. First, an optimized grain topology deformation technology is utilized for studying the hot compression e ect on the topology of grain deformation. Second, the overlapping grain topological structures are optimized by using an independent component analysis method, and the influence of various thermomechanical parameters on the nucleation process, grain growth kinetics, and mean grain sizes observed during drX are explored. Experimental study shows that the average relative root mean square error(rrMSE) of the mean grain diameter obtained by the regular CA model is equal to 0.173, while the magnitude calculated using the proposed optimized CA model is only 0.11. This paper pro?poses a novel combined CA model for simulating the microstructural evolution of 42 CrMo cast steel, which notably uses a ICA?based grain topology deformation method to optimize the overlapping grain topological structures in simulation.

关键词： 42CrMo cast steel dynamic recrystallization Cellular automaton Grain topology Independent component analysis

Understanding of the relationship between the Properties of Cu(In,Ga)Se2 Solar Cells and the Structure of Ag Network Electrodes

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ENErGY & ENVIrONMENTAL MATErIALS 2024年第6期7卷 246-253页

作者： Yoo, Hyesun Quy, Hoang Van Lee, Inpyo Jo, Seung Taek Hong, Tae Ei Kim, Junho Yoo, dae-Hwang Shin, Jinwook Commerell, Walter Kim, dae-Hwan roh, Jong Wook Kyungpook Natl Univ Reg Leading Res Ctr RLRC Smart Energy Syst Daegu 37224 Gyeongsangbug D South Korea Kyungpook Natl Univ Dept Hydrogen & Renewable Energy Daegu 47922 South Korea Kyungpook Natl Univ Dept Nano & Adv Mat Sci & Engn Daegu 37224 Gyeongsangbug D South Korea daegu Gyeongbuk Inst Sci & Technol dGIST Div Energy Technol Daegu 42988 South Korea Incheon Natl Univ Dept Phys Nano Photoelect Device Lab Incheon 22012 South Korea TH Ulm THU Prittwitzstr 10 D-89081 Ulm Germany

The relation between the structure of the silver network electrodes and the properties of Cu(In,Ga)Se2 (CIGS) solar cells is systemically investigated. The Ag network electrode is deposited onto an Al:ZnO (AZO) thin film, employing a self-forming cracked template. Precise control over the cracked template's structure is achieved through careful adjustment of temperature and humidity. The Ag network electrodes with different coverage areas and network densities are systemically applied to the CIGS solar cells. It is revealed that predominant fill factor (FF) is influenced by the figure of merit of transparent conducting electrodes, rather than sheet resistance, particularly when the coverage area falls within the range of 1.3-5%. Furthermore, a higher network density corresponds to an enhanced FF when the coverage areas of the Ag networks are similar. When utilizing a thinner AZO film, CIGS solar cells with a surface area of 1.0609 cm2 exhibit a notable performance improvement, with efficiency increasing from 10.48% to 11.63%. This enhancement is primarily attributed to the increase in FF from 45% to 65%. These findings underscore the considerable potential for reducing the thickness of the transparent conductive oxide (TCO) in CIGS modules with implications for practical applications in photovoltaic technology.

关键词： CIGS large-area solar cell metal mesh metallic network transparent electrode

Simulation and experimental research on extra-squeeze forming method during gradient sand molding

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China Foundry 2022年第4期19卷 288-298页

作者： Er-biao Jiang Zhong-de Shan Guang Cheng Shao-zong Wang Zhao-xian Gu Xin-lei Wang State Key Laboratory of Advanced forming technology and Equipment China Academy of Machinery Science and Technology Group Co.Ltd.Beijing 100044China Nanjing University of Aeronautics and Astronautics Nanjing 210016China Beijing Union University Beijing 100101China

The flexible extrusion forming process (FEFP) is a sand mold patternless manufacturing technology that enables digital near-net shaping of complex sand molds. But, it is difficult to achieve the gradient sand molds with high surface strength and strong interior permeability by FEFP. To solve this problem, an extra-squeeze forming method based on FEFP for gradient sand mold was developed. To further reveal the extra-squeeze forming mechanism, based on the Johnson-Kendall-roberts (JKr) theory and “gluing” notions, the single and double-sided squeeze models of gradient sand molds were established using the EdEM software. The squeezing processes of sand molds with different cavity depths of 60, 100, 140, 180, and 220 mm were systemically studied under single and double-sided squeeze conditions. The variation in the void fraction of sand mold as also investigated at a variety of extra-squeeze distances of 2, 3, 4, 5, and 6 mm, respectively. Simulation and test results show that a deeper cavity depth weakens the extrusion force transmission, which leads to a decrease in strength. The sand mold permeability and void fraction are identified to be positively correlated, while the tensile strength and void fraction appear to be negatively correlated. The void fraction of sand molds decreases with a longer extra-squeeze distance. A 6 mm extra-squeeze distance for the sand mold with 220 mm cavity depth results in a 26.8% increase in tensile strength with only a 5.7% reduction in the permeability. Hence, the extra- squeeze forming method can improve the quality of the sand mold by producing a gradient sand mold with high surface strength and strong interior permeability.

关键词： patternless casting gradient squeeze sand mold performance discrete element simulation void fraction

Covalent Organic Framework with 3d Ordered Channel and Multi-Functional groups Endows Zn Anode with Superior Stability

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Nano-Micro Letters 2024年第4期16卷 350-363页

作者： Bin Li Pengchao ruan Xieyu Xu Zhangxing He Xinyan Zhu Liang Pan Ziyu Peng Yangyang Liu Peng Zhou Bingan Lu Lei dai Jiang Zhou School of Chemical Engineering North China University of Science and TechnologyTangshan 063009People’s Republic of China School of Materials Science and Engineering Central South UniversityChangsha 410083People’s Republic of China State Key Laboratory for Mechanical Behavior of Materials Xi’an Jiaotong UniversityXi’an 710049People’s Republic of China Hunan Provincial Key defense Laboratory of High Temperature Wear‑resisting Materials and Preparation technology Hunan University of Science and TechnologyXiangtan 411201People’s Republic of China School of Physics and Electronics Hunan UniversityChangsha 410082People’s Republic of China

Achieving a highly robust zinc(Zn)metal anode is extremely important for improving the performance of aqueous Zn-ion batteries(AZIBs)for advancing“carbon neutrality”society,which is hampered by the uncontrollable growth of Zn dendrite and severe side reactions including hydrogen evolution reaction,corrosion,and passivation,***,an interlayer containing fluorinated zincophilic covalent organic framework with sulfonic acid groups(COF-S-F)is developed on Zn metal(Zn@COF-S-F)as the artificial solid electrolyte interface(SEI).Sulfonic acid group(-SO_(3)H)in COF-S-F can effectively ameliorate the desolvation process of hydrated Zn ions,and the three-dimensional channel with fluoride group(-F)can provide interconnected channels for the favorable transport of Zn ions with ion-confinement effects,endowing Zn@COF-S-F with dendrite-free morphology and suppressed side ***,Zn@COF-S-F symmetric cell can stably cycle for 1,000 h with low average hysteresis voltage(50.5 m V)at the current density of 1.5 m A cm^(-2).Zn@COF-S-F|Mn O_(2)cell delivers the discharge specific capacity of 206.8 m Ah g^(-1)at the current density of 1.2 A g^(-1)after 800 cycles with high-capacity retention(87.9%).Enlightening,building artificial SEI on metallic Zn surface with targeted design has been proved as the effective strategy to foster the practical application of high-performance AZIBs.

关键词： Aqueous Zn ion batteries Covalent organic framework Interfacial modification Zn ion flux regulation desolvation effect