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Journal of Iron and Steel Research International 2014年第1期21卷 104-108页

作者： Zhi-tao HUANG wen-huai tian School of Materials Science and Engineering University of Science and Technology Beijing

Thermal diffusion salt-bath vanadizing was finished for Crl2MoV die steel, in order to investigate the properties of vanadium carbide coatings related with the Mo contents in Crl2MoV die steel. Scanning electron micro- scopic observation reveals that Mo can decrease the growth rate of coating as a carbide forming element. Besides, Mo element can promote grain refinement of the coating. X-ray diffraction analysis shows that the different Mo contents have no influence on the phase structure of the coatings. Energy dispersive spectrum analysis and mechanical properties test show that Mo can diffuse into the coating and make a strengthening effect on the coating.

关键词： vanadium carbide salt-bath carbide forming element grain refinement mechanical property

Microstructure and phase composition of hypoeutectic Te–Bi alloy as evaporation source for photoelectric cathode

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International Journal of Minerals,Metallurgy and Materials 2018年第5期25卷 584-590页

作者： Bao-guang Wang wen-hui Yang Hong-ye Gao wen-huai tian School of Materials Science and Engineering University of Science and Technology Beijing Faculty of Engineering Sciences Kyushu University

A hypoeutectic 60Te–40Bi alloy in mass percent was designed as a tellurium atom evaporation source instead of pure tellurium for an ultraviolet detection *** alloy was prepared by slow solidification at about 10^(-2) K·s^(-1).The microstructure,crystal structure,chemical composition,and crystallographic orientation of each phase in the as-prepared alloy were investigated by optical microscopy,scanning electron microscopy,X-ray diffraction,electron backscatter diffraction,and transmission electron *** experimental results suggest that the as-prepared 60Te–40Bi alloy consists of primary Bi_2Te_3 and eutectic Bi_2Te_3/Te *** primary Bi_2Te_3 phase has the characteristics of faceted *** eutectic Bi_2Te_3 phase is encased by the eutectic Te phase in the eutectic *** purity of the eutectic Te phase reaches 100wt%owing to the slow *** the eutectic phases,the crystallographic orientation relationship between Bi_2Te_3 and Te is confirmed as[0001]_(Bi2 Te3)//[1213]_Te and the direction of Te phase parallel to[1120]_(Bi2 Te3)is deviated by 18°from N(2111)_Te.

关键词： Te–Bi alloy microstructure orientation misfit

In situ backscattered electron imaging study of the effect of annealing on the deformation behaviors of Ni electroformed from additive-free and saccharin-containing sulfamate solutions

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International Journal of Minerals,Metallurgy and Materials 2019年第1期26卷 114-123页

作者： Kai Jiang Hiroaki Nakano Satoshi Oue Tatsuya Morikawa wen-huai tian School of Materials Science and Engineering University of Science and Technology Beijing Faculty of Engineering Kyushu University

The Ni samples were electroformed from additive-free(AF) and saccharin-containing(SC) sulfamate solutions, respectively. In situ backscattered electron(BSE) imaging, electron backscatter diffraction(EBSD), and electron-probe microanalysis(EPMA) were used to investigate the effect of annealing on the deformation behaviors of the AF and SC samples. The results indicate that columnar grains of the as-deposited AF sample had an approximated average width of 3 μm and an approximated aspect ratio of 8. The average width of columnar grains of the as-deposited SC sample was reduced to approximately 400 nm by the addition of saccharin to the electrolyte. A few very-large grains distributed in the matrix of the SC sample after annealing. No direct evidence indicated that S segregated at the grain boundaries before or after annealing. The average value of the total elongations of the SC samples decreased from 16% to 6% after annealing, whereas that of the AF samples increased from 18% to 50%. The dislocation recovery in grain-boundary areas of the annealed AF sample was reduced, which contributed to the appearance of microvoids at the triple junctions. The incompatibility deformation between very-large grains and fine grains contributed to the brittle fracture behavior of the annealed SC Ni.

关键词： backscattered electron imaging annealing electroformed Ni sulfamate solution deformation behaviors

Microstructural evolution in electroformed nickel shaped-charge liners with nano-sized grains undergone deformation at ultrahigh strain rate

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International Journal of Minerals,Metallurgy and Materials 2010年第5期17卷 617-623页

作者： Feng Yang Chun-hua Li Sheng-wei Cheng Lei Wang wen-huai tian School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China

Nickel shaped-charge liners with nano-sized grains were prepared by the electroforming technique, and the deformation at ultrahigh strain rate was performed by explosive detonation. The as-formed and post-deformed microstructures of electroformed nickel shaped-charge liners with nano-sized grains were observed by means of transmission electron microscopy, and the orientation distribution of the grains was analyzed by the electron backscattering pattern （EBSP） technique. The melting phenomenon in the jet fragment and the recovery and recrystallization in the slug after plastic deformation at ultrahigh-strain rate were observed in the ultrafine-grained nickel shaped-charge liners. The research evidence shows that dynamic recovery and recrystallization play an important role in plastic deformation at ultrahigh strain rate.

关键词： electroformed nickel nanosized plastic deformation electroformation microtexture dynamic recovery and recrystallization

Microstructural evolution and mechanical properties of a low-carbon quenching and partitioning steel after partial and full austenitization

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International Journal of Minerals,Metallurgy and Materials 2016年第8期23卷 906-919页

作者： Wan-song Li Hong-ye Gao Hideharu Nakashima Satoshi Hata wen-huai tian School of Materials Science and Engineering University of Science and Technology Beijing Interdisciplinary Graduate School of Engineering Sciences Kyushu University

In this work, low-carbon steel specimens were subjected to the quenching and partitioning process after being partially or fully austenitized to investigate their microstructural evolution and mechanical properties. According to the results of scanning electron microscopy and transmission electron microscopy observations, X-ray diffraction analysis, and tensile tests, upper bainite or tempered martensite appears successively in the microstructure with increasing austenitization temperature or increasing partitioning time. In the partially austenitized specimens, the retained austenite grains are carbon-enriched twice during the heat treatment, which can significantly stabilize the phases at room temperature. Furthermore, after partial austenitization, the specimen exhibits excellent elongation, with a maximum elongation of 37.1%. By contrast, after full austenitization, the specimens exhibit good ultimate tensile strength and high yield strength. In the case of a specimen with a yield strength of 969 MPa, the maximum value of the ultimate tensile strength reaches 1222 MPa. During the partitioning process, carbon partitioning and carbon homogenization within austenite affect interface migration. In addition, the volume fraction and grain size of retained austenite observed in the final microstructure will also be affected.

关键词： low-carbon steel quenching partitioning microstructure mechanical properties interfaces

Electrochemical properties of niobium and phosphate doped spherical Li-rich spinel LiMn2O4 synthesized by ion implantation method

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Chinese Chemical Letters 2017年第7期28卷 1438-1446页

作者： Wei Li Gao-Wa Siqin Zhi Zhu Lu Qi wen-huai tian Department of Materials Physics and Chemistry School of Materials Science and EngineeringUniversity of Science and TechnologyBeijing 100083China New Energy Materials and Technology Laboratory Department of Applied ChemistryCollege of Chemistry and Molecular EngineeringPeking UniversityBeijing 100871China

Spherical Li-rich lithium manganese oxide（LMO） spinel material was synthesized by an ion implanted method assisted by polyalcohol doped with Niobium and Phosphate *** material was characterized by scanning electron microscopy,X-ray diffraction and BET specific surface area *** electrochemical performances were investigated with galvanostatic techniques and cyclic *** synthesis process was investigated with TG/*** results show that the lithium ion can be immersed into the pore of manganese dioxide at a low temperature with the ion implanted *** prepared materials have a higher discharge capacity and better crystallization than those prepared by solid phase *** doped Nb can improve the capacity of the Li-rich LMO spinel and reinforce the crystal growth along（111） and（400） *** crystal grains show circular and smooth morphology,which makes the specific surface area greatly ***-doped LMO spinel exhibits good high-rate capacity and structure *** prepared Li（1.09）Mn（1.87）Nb（0.031）O（3.99）（PO4）（0.021）delivers a discharge capacity of 119mAhg^-1 at 0.2C（1C=148mAg^-1） and 112.8 mAhg^-1 at 10 C,the discharge capacity retention reaches 98% at 1 ℃ after 50 cycles at 25 ℃ and 94% at 55 ℃.

关键词： Spinels Ion implantation Li-ion batteries LiMn2O4 Doping

Effect of lower bainite/martensite/retained austenite triplex microstructure on the mechanical properties of a low-carbon steel with quenching and partitioning process

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International Journal of Minerals,Metallurgy and Materials 2016年第3期23卷 303-313页

作者： Wan-song Li Hong-ye Gao Zhong-yi Li Hideharu Nakashima Satoshi Hata wen-huai tian School of Materials Science and Engineering University of Science and Technology Beijing Interdisciplinary Graduate School of Engineering Sciences Kyushu University

We present a study concerning Fe-0. 176C-1.31Si-1.58Mn-0.26Al-0.3Cr （wt%） steel subjected to a quenching and partitioning （Q＆P） process. The results of scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and tensile tests demon- strate that the microstructures primarily consist of lath martensite, retained austenite, lower bainite （LB）, and a small amount of tempered martensite; moreover, few twin austenite grains were observed. In the microstrucmre, three types of retained austenite with different sizes and morphologies were observed： blocky retained austenite （-300 nm in width）, film-like retained austenite （80-120 nm in width）, and ul- tra-fine film-like retained austenite （30-40 nm in width）. Because of the effect of the retained austenite/martensite/LB triplex microstructure, the specimens prepared using different quenching temperatures exhibit high ultimate tensile strength and yield strength. Furthermore, the strength effect of LB can partially counteract the decreasing strength effect of martensite. The formation of LB substantially reduces the amount of retained austenite. Analyses of the retained austenite and the amount of blocky retained austenite indicated that the carbon content is critical to the total elongation of Q＆P steel.

关键词： low-carbon steel quenching partitioning retained austenite rnicrostructure mechanical properties

Effects of surface morphology on tribological properties of Arapaima gigas scales

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Friction 2024年第7期12卷 1469-1482页

作者： Shuaijun ZHANG Pengpeng BAI Xiangli wen Chengwei wen Hui CAO Wanyou YANG Yu tian State Key Laboratory of Tribology in Advanced Equipment Department of Mechanical EngineeringTsinghua UniversityBeijing 100084China Key Laboratory of Bionic Engineering(Ministry of Education China)Jilin UniversityChangchun 130022China

The remarkable mechanical adaptability of arapaima(Arapaima gigas)scales has made them an important subject of ***,no research has been conducted into their tribological properties,which are crucial for the protectability and flexibility of *** this study,by combining morphological characterizations,friction experiments,and theoretical analyses,the relationship between the surface morphology and tribological properties of arapaima scales is *** results indicate that arapaima scales exhibit varying surface morphologies in different *** specifically,the exposed regions of scales feature grooves and a circulus,whereas the covered regions exhibit *** specific surface morphology of arapaima scales produces varying tribological properties across different regions and sliding *** unique tribological properties of arapaima scales influence the forces received from predator attacks and neighboring scales,directly influencing the arapaima’s protective *** study provides new insights into the mechanisms of natural flexible dermal armors,and it has potential applications in personal protective systems.

关键词： arapaima scales surface morphology tribological properties protectability

An analytical model of hot rolling force for a thick plate by combining globally optimal approximation yield criterion and egg-circular velocity field

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Journal of Iron and Steel Research International 2024年第3期31卷 647-659页

作者： Shun-hu Zhang Yi Zhang wen-hao tian Yan Li Shagang School of Iron and Steel Soochow UniversitySuzhou 215021JiangsuChina

For the sake of solving the problem that it is difficult to be integrated for the Mises specific plastic power due to its nonlinearity,a new linear criterion,named the globally optimal approximation criterion,is constructed by the polygonal approximation to the Mises *** new criterion is proved to be the linear function of the principal stress componentsσ1,σ2 andσ3 and the trajectory of it on theπ-plane is a non-equiangular but equilateral dodecagon intersecting the Mises *** theoretical results of the current criterion described by the Lode stress parameters are in excellent accordance with the experimental ***,according to the trend that the metallic flow velocity between rollers aggrandizes gradually from the inlet to the outlet during the hot rolling of a thick plate,a biomimetic velocity field is proposed in which the horizontal velocity component fits the egg-circular curve *** velocity field and its simulated results agree quite ***,using the determined linear criterion,energy analysis of the constructed velocity field is utilized to obtain the interior deformation power,while the vector decomposition approach is utilized to obtain the frictional power and shear *** this basis,the overall power is obtained and the analytical solutions are generated for the rolling torque,rolling force and the coefficient of the stress state under different egg curves by minimizing the neutral ***,the parameter optimization of the characteristic parameterρwhich affects the slope of the egg-circular curve is carried out and the best egg-circular curve which can minimize the energy consumption is *** best agreement between the theoretical and observed values of rolling force and rolling torque is under this curve,and the mean relative errors of the rolling torque and rolling force are no more than 2.93%,while the maximum error is no more than 8.35%.

关键词： Yield criterion Plastic deformation Rolling force Velocity field Analytical solution

A new integrated model of deformation resistance and its application in prediction of rolling force of a thick plate

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Journal of Iron and Steel Research International 2024年第4期31卷 882-893页

作者： Shun-hu Zhang Yan Li Li-zhi Che wen-hao tian Shagang School of Iron and Steel Soochow UniversitySuzhou 215021JiangsuChina

The prediction accuracy of existing models of the rolling force of a thick plate is always very *** address this problem,a high-precision genetic algorithm-backpropagation network(GA-BP)model of deformation resistance was built,and its integration with the traditional fitted model was further ***,a novel rolling force model was obtained by embedding the integration model of deformation resistance in the original model of rolling *** to this research idea,the industrial data are normalized at *** this basis,the interactions among the process parameters were disclosed through the variance analysis,and then described by various virtual *** factors are set as part of input ***,the optimal structure of the GA-BP model of deformation resistance was determined and an integration model of deformation resistance was ***,a novel rolling force model is obtained by substituting the traditional fitted deformation resistance into the Sims model with the integration model of the deformation *** results proves that the introduction of virtual factors can increase the hit rate of±5%from 75.8%to 78%and can reduce the root mean square error from 4.72%to 4.48%.Besides,it is found that the mean relative error of the traditional fitted deformation resistance is 0.142,while that of the modified deformation resistance is only *** addition,the mean relative error in the original rolling force model is 0.145,while that of the present model is only 0.03.

关键词： Integration model-Deformation resistance Variance analysis Virtual factor Genetic algorithm-backpropagation network model