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Relaxation of Deformed Austenite and Refinement of Bainite in a Nb-Containing Microalloyed Steel

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Journal of university of science and technology beijing 2001年第3期8卷 214-217页

作者： shanwu yang, xuemin wang, chengjia shang, xinlai he, yi yuan material science and engineering school, university of science and technology beijing, beijing 100083, china material science and Eng. school Univ. of Sci. and Technol. Beijing Beijing 100083 China

By means of stress relaxation and strain-induced precipitation in deformed austenite, bainite with micron sheaves size was obtained in Nb-containing steel. Microstructures of deformed samples isothermally relaxed for various time followed by cooling in water were examined. Stress relaxation test and transmission electron microscopy (TEM) were employed to detect precipitation of microalloy elements, such as Nb, Ti, during isothermal holding after deformation. All the samples were constituted by lath-like bainite along with acicular ferrite, but the size of bainitic sheaves and the amount of acicular ferrite were changed with relaxation time. To achieve optimum refinement, relaxation should be confined in the stage when the precipitates have sufficiently grown and started to coarsen. The sample having not undergone relaxation does not exhibit obvious refinement despite of its higher dislocation density. These results indicate that relaxation promotes bainite to refine, which is because deformed austenitic grains are divided by dislocation walls formed during relaxation and acicular ferrite formed before bainitic transformation.

关键词： stress relaxation strain induced precipitation refinement

Stability of Ultra-fine Microstructures during Tempering

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Journal of university of science and technology beijing 2001年第2期8卷 119-122页

作者： shanwu yang, chengjia shang,xinlai he, xuemin wang, yi yuan (material science and engineering school, university of science and technology beijing, beijing 100083, china) material Sci. and engineering school University of Science and Technology Beijing 100083 China

The stability of ultra-fine microstructure during tempering at 650 degreesC was investigated on a Nb-containing steel. The steel had undergone 5 passes controlled rolling, then was relaxed lair cooled) to 730 degreesC: and cooled in water. The evolution of microstructure was that, in early stage of tempering, no obvious change was detected by means of optical microscopy while dislocation cells were formed inside bainitic laths. With further tempering, bainitic laths started to coalesce in some regions. Finally, polygonal ferrite was formed while hardness decreased dramatically. Some samples taken from the same primary plate were reheated at 930 degreesC for 0.5 h followed by quenching into water before tempering. Despite their lower original hardness, the reheated samples softened Faster during tempering. Ferrite was quickly formed in the reheated samples. These results indicate that the evolution of microstructures towards equilibrium during tempering of the steel is mainly determined by whether dislocations are pinned rather than the dislocation density.

关键词： microalloyed steel bainite tempering

Recent progress on impact induced reaction mechanism of reactive alloys

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Defence technology（防务技术） 2024年第7期37卷 69-95页

作者： Yansong yang Chuanting wang yuanpei Meng Yue Ma Lei Guo yuan he Zhichao Sun Yong he school of Mechanical engineering Nanjing University of Science and TechnologyNanjing 210094JiangsuChina

In recent years,in order to improve the destructive effectiveness of munitions,the use of new types of destructive elements is an important way to improve destructive *** a new type of reactive material,reactive alloy contains a large portion of reactive metal elements(Al,Mg,Ti,Zr,etc.),which breaks up under high-velocity impact conditions,generating a large number of high-temperature combustible fragments,which undergo a violent combustion reaction with *** with traditional metal polymers(Al-PTFE)and other reactive composites,it has higher density and strength,excellent mechanical properties and broader application ***,researchers have mainly investigated the impact energy release mechanism of reactive alloys through impact tests,and found that there are several important stages in the process of the material from fragmentation to reaction,i.e.,impact fragmentation of the material,rapid heating and combustion *** paper focuses on three problems that need to be solved in the impact-induced energy release process of reactive alloys,namely:the fragmentation mechanism and size distribution law of the fragments produced by the impact of the material on the target,the relationship between the transient temperatures and the size of the fragments,and the reaction temperatures and size thresholds of the fragments to undergo the chemical *** current status of the research of the above problems is reviewed,some potential directions to reveal the impact induced reaction mechanism of reactive alloy is discussed.

关键词： Reactive alloys Impact Fragmentation Mass and size distribution Shock temperature rise Adiabatic shear Combustion

Surface Metallurgy of Nickle Base Superalloy

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International Journal of Minerals,Metallurgy and materials 1999年第1期13卷 47-49页

作者： Xu Zhang Zhongmin yang Jianxin Dong Xishan Xie yuan Gao Zhong Xu (material science and engineering school, university of science and technology beijing, beijing 100083, china)(Institute of Surface engineering, Taiyuan university of technology, Taiyua material science and engineering school University of Science and Technology Beijing Beijing 100083 China Institute of Surface engineering Taiyuan University of Technology Taiyuan 030024 China

The Double Glow Plasma Surface Alloying Technique, the Xu-Tee Process, is a new method to produce high quality alloying layer on the surface of less expensive materials. By using thes technique, the surface alloying layer similar to superalloy Inconel 625 has been obtained on the surface of three kinds of melallic materials (low carbon steel, industrial pure iron, stainless steel Cr18Ni9). The results of the composition and microstructure analyzed by Scanning Electron Microscopy (SEM) and X-Ray Uffrachon (XRD) show that the alloying layer consistS of y matrix and several precipitates (Laves intermetallic phase and carbide etc.). The electrochemical corrosion results show that the surface alloying layer formed on the surface of stainless steel and industrial pure iron have better corrosion resistance than that of nickel base alloy inconel 625 and stainless steel Cr18Ni9 in 3.5%NaCl solution. The exper iments indicate that it is an effective way to obtain the gradient surface alloying layer on the surfaces of steels by using Double Glow Plasma Surface Alloying Technique.

关键词： double glow nickel base alloy plasma surface alloying

Carbon Nitride Films Deposited on Pt Substrates byMicrowave Plasma Chemical Vapor Deposition

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International Journal of Minerals,Metallurgy and materials 2000年第1期14卷 42-44页

作者： Yongping Zhang Yousong Gu Xiangrong Chang Zhongzhuo Tian Dongxia Shi Xiufang Zhanga Lei yuan material science and engineering school, university of science and technology beijing, beijing 100083, china beijing Laboratory of Vacuum Physics, Institut material science and engineering school University of Science and Technology Beijing Beijing 100083 China beijing Laboratory of Vacuum Physics Institute of Physics Chinese Academy of Sciences Beijing 100080 China

Carbon nitride thin films have been synthesized on polycrystalline Pt substrates using microwave plasma chemical vapor de- position (MPCVD) technique. The N/C atomic ratio is close to the stoichiometric value 1.33 of C_3N_4. The experimental X-ray diffraction spectra contain all the strong peaks of α-C_3N_4 and β -C_3N_4. The films are a mixture of α-C_3N_4 and β -C_3N_4. The observed Raman and FT- IR spectra support the existence of C-N covalent bond in carbon nitride compound. The bulk modulus detected by Nano II nanoindentor is up to 349 GPa.

关键词： carbon nitride MPCVD, thin film deposition

Effect of post rolling stress on phase transformation behavior of microalloyed dual phase steel

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Journal of Iron and Steel Research International 2024年第3期31卷 688-699页

作者： Wen-quan Sun Sheng-yi Yong Tie-heng yuan Ting-song yang An-rui he Chao Liu Rui-chun Guo National engineering Research Center for Advanced Rolling and Intelligent Manufacturing University of Science and Technology BeijingBeijing 100083China

The slow phase transformation of microalloyed dual phase steel makes the nonuniform stress and temperature fields during the post rolling cooling process have a significant impact on the phase transformation *** the relatively slow phase transformation of DP780 steel within the microalloyed dual phase steel series,the influence of stress on the phase transformation behavior of DP780 steel was *** quantify the nonuniform thermal and stress conditions in the steel coil,a thermo-mechanical coupled finite element model of the hot-rolled strip cooling process was *** on the simulation data,DP780 steel was chosen as the research material,and Gleeble 3500 thermal simulation equipment was used for experimental *** thermal expansion curves were analyzed through regression to establish the dynamic model of DP780 steel phase transformation under ***,metallographic analysis was conducted to determine phase transformation type and grain size of DP780 *** results confirmed that the stress promotes the occurrence of semi-diffusion-type bainite ***,an appropriate level of stress facilitates the growth of bainitic grains,while the increased stress inhibits the growth of ferritic grains.

关键词： Microalloyed dual phase steel Stress Bainitic transformation Grain Finite element method

Simplified p-i-n Perovskite Solar Cells with a Multifunctional Polyfullerene Electron Transporter

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Chinese Journal of Polymer science 2024年第8期42卷 1060-1066页

作者： Fei-Fei wang Tian-Xiao Liu Ze-Wei Cui Ling-yuan wang Yun-Jie Dou Xiao-Yu Shi Si-Wei Luo Xiao-Dong Hu Zhi-Jun Ren yang-yang Liu Yu Zhao shang-shang Chen State Key Laboratory of Coordination Chemistry MOE Key Laboratory of High Performance Polymer Materials&TechnologySchool of Chemistry and Chemical EngineeringNanjing UniversityNanjing 21003China

In prevailing p-i-n perovskite solar cells(PSCs),solution-processible fullerene molecules are widely used as electron-transporting layers(ETLs)but they typically suffer from poor uniformity and undesirable stability ***,a separate bathocuproine(BCP)layer is needed to block hole tran sfer,increasing fabrication complexity and ***,we address these limitations by develo ping a novel polymeric ETL(named PF BCP)synthesized by polymerizing C_(60)with *** innovative material achieves both efficient electron transport and hole blocking,while its excellent uniformity minimizes interface recombination and enhances ***,our blade-coated PSCs utilizing PFBCP achieve a high power conversion efficiency exceeding 22%and retain 91%of initial efficiency after 1200 h of light *** development not only paves the way for commercially viable PSCs but also opens avenues for future ETL design to realize even more efficient and stable PSCs.

关键词： Polyfullerene Perovskite solar cells Electron transporter Stability

Advances of high-performance LiNi_(1-x-y)Co_(x)M_(y)O_(2) cathode materials and their precursor particles via co-precipitation process

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Particuology 2024年第3期86卷 67-85页

作者： Wenbiao Liang yin Zhao Liyi Shi Zhuyi wang yi wang Meihong Zhang Shuai yuan school of materials science and engineering Shanghai UniversityShanghai200444China Research Center of Nanoscience and Nanotechnology Shanghai UniversityShanghai200444China Emerging Industries Institute Shanghai UniversityJiaxingZhejiang314006China

Layered LiNi_(1-x-y)Co_(x)M_(y)O_(2)(M=Mn or Al)is a promising cathode material for lithium-ion batteries due to its high specific capacity and acceptable manufacturing ***,the polycrystalline LiNi_(1-x-y)Co_(x)M_(y)O_(2) cathode material suffers from disordered orientation of primary particles and poor geometric symmetry of secondary particles,which severely hampers the migration of Lit ***,the resulting anisotropy accelerates the disintegration of the secondary particle structure,significantly affecting the electrochemical performance of the polycrystalline *** spite of less grain boundary,the single-crystal LiNi_(1-x-y)Co_(x)M_(y)O_(2) cathodes still suffer from severe microcracks generated by repeated planar gliding during cycling,which poses a great challenge to the cycling stability of single-crystal ***'s worth noting that the microstructure of the cathode material is mainly inherited from its ***,it is necessary to deeply understand the influence of the microstructure of Ni_(1-x-y)Co_(x)M_(y)(OH)2 on the electrochemical properties of LiNi_(1-x-y)Co_(x)M_(y)O_(2) cathode materials,so as to optimize the production process of preparing high-performance cathode *** this review,we summarize recent advances in the research and development of Ni-rich cathode precursor ***,the challenges faced by the Ni-rich hydroxide precursor materials are presented,including the effect of primary particle morphology and arrangement on the electrochemical performance of cathode materials,the influence of secondary particle morphology on lithium insertion reactions in cathode,and the effect of particle size on the microcracking of single-crystal ***,the presentation of the conventional co-precipitation reactor,the mechanism of precursor particle growth,and the influence of coprecipitation parameters are described in ***,the strategies are systematically discussed to solve the cha

关键词： Lithium-ion batteries Cathode materials Co-precipitation Ni-rich layered oxides Single crystal Precursor particles

Fe-Zn alloy, a new biodegradable material capable of reducing RoS and inhibiting oxidative stress

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Regenerative Biomaterials 2024年第2期3卷 114-122页

作者： Shuaikang yang Weiqiang wang Yanan Xu Yonghui yuan Shengzhi Hao school of materials science and engineering Dalian University of TechnologyDalian 116024PR China Clinical Research Center for Malignant Tumor of Liaoning Province Cancer Hospital of Dalian University of TechnologyShenyang 110042PR China

Fe-based biodegradable materials have attracted significant attention due to their exceptional mechanical properties and favorable ***,research on Fe-based materials mainly focuses on regulating the degradation ***,excessive release of Fe ions during material degrada-tion will induce the generation of reactive oxygen species(ROS),leading to oxidative stress and ***,the con-trol of RoS release and the improvement of biocompatibility for Fe-based materials are very *** this study,new Fe-Zn alloys were prepared by electrodeposition with the intention of using Zn as an antioxidant to reduce oxidative damage during alloy ***,the impact of three potential degra-dation ions(Fe^(2+),Fe^(3+),Zn^(2+))from the Fe-Zn alloy on human endothelial cell(EC)activity and migration ability was ***,cell adhesion,cell activity,ROs production and DNA damage were assessed at various locations surrounding the ***,the influence of different concentrations of Zn^(2+) in the medium on cell viability and ROS production was *** levels of ROS exhibited evident toxic effects on ECs and promoted DNA *** an antioxidant,Zn?+effectively reduced ROS production around Fe and improved the cell viability on its surface at a concentration of 0.04 mmol/*** findings demonstrate that Fe-Zn alloy can attenuate the ROS generated from Fe degradation therebyenhancingcytocompatibility.

关键词： biodegradable iron Fe-Zn alloys reactive oxygen species oxidative stress cytocompatibility