检索结果-南通市图书馆

Preparation of Cu-based Bulk Metallic Glass Matrix Composites

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2006年第1期22卷 73-77页

作者： yufeng sun Yuren WANG Bingchen WEI Weihuo LI Research Center for Materials Department of Materials Science and Engineering Zhengzhou UniversityZhengzhou 450002 China National Microgravity Laboratory Institute of Mechanics Chinese Academy of Sciences Beijing 100080 China

Cu47Ti34Zr11Ni8 bulk metallic glass （BMG） matrix composites containing in situ formed TiC particles and 5-TiCu dendrite phase were developed by copper mold cast. The thermal stability and microstructure of the composites are investigated. Room temperature compression tests reveal that the composite samples exhibit higher fracture strength and distinct plastic strain of 0.2%-0.5%, comparing with that of the corresponding Cu47Ti34Zr11Ni8 monolithic BMG.

关键词： Bulk metallic glasses Shear bands Mechanical properties Composites

Effect of Stacking Fault Energy on the Grain Structure Evolution of FCC Metals During Friction Stir Welding

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2020年第7期33卷 1001-1012页

作者： Xiaochao Liu yufeng sun Tomoya Nagira Kohsaku Ushioda Hidetoshi Fujii Joining and Welding Research Institute Osaka University11-1 MihogaokaIbarakiOsaka 567-0047Japan School of Materials Science and Engineering Northwestern Polytechnical UniversityXi'an 710072China School of Materials Science and Engineering Zhengzhou UniversityZhengzhou 450001China

The effect of stacking fault energy(SFE) on the grain structure evolution of face-centered cubic metals during friction stir welding was investigated by using pure aluminum,pure copper and Cu-30 Zn alloy as experiment *** "stop action" and rapid cooling were employed to "freeze" the microstructure of the flowing materials around the *** materials were used to show the streamline of the material *** microstructures of the three materials at different welding stages were contrastively studied by the electron backscatter diffraction *** results show that at the material flow stage,as the SFE decreases,the grain structure evolution changes from the continuous dynamic recrystallization to discontinuous dynamic recrystallization,and further to the dynamic equilibrium between the annealing twinning due to thermally activated grain boundary migration and the twin destruction during the plastic *** to different grain structure evolution mechanisms,the grain structure at the end of the material flow is greatly *** in copper,a lot of dislocations remain,which gives rise to the static recrystallization occurring during the subsequent cooling stage.

关键词： recrystallization grain welding

Exploring a balance between strength and ductility of hexagonal BN nanoplatelet reinforced ZK61 magnesium composite

在线全文

学校读者我要写书评

暂无评论

Journal of Magnesium and Alloys 2024年第5期12卷 1899-1910页

作者： Kewei Zhang Xiaolong Lu yufeng sun Shaokang Guan Yao Chen School of Materials Science and Engineering Zhengzhou UniversityZhengzhou 450001China Key Laboratory of Advanced Magnesium Alloys in Henan Province Zhengzhou UniversityZhengzhou 450002China Key Laboratory of Advanced Materials Processing&Mold Ministry of EducationZhengzhou 450002China School of Mechanical and Electrical Engineering Soochow UniversitySuzhou 215021China

The practical applications of magnesium(Mg)alloys are usually beset by their relatively low strength and limited *** we attempt to fabricate hexagonal BN nanoplatelet(BNNP)reinforced ZK61 magnesium composites using a combination of spark plasma sintering and friction stir *** resulting composites exhibit microstructural characteristics of homogeneous dispersion of BNNP in Mg matrix with refined equiaxed grains and(0002)basal texture roughly surrounding the pin column *** electron microscopy observation illustrates that trace amounts of Mg_(3)N_(2)and MgB_(2)form at BNNP-Mg interface,in which Mg_(3)N_(2)locates at the basal plane of a BNNP and MgB_(2)grows at its open *** spatial distribution of Mg_(3)N_(2)and MgB_(2)facilitates interfacial wetting and stronger BNNP-Mg interface in such a way that interfacial products act as anchors bonding between *** comparison with monolithic ZK61 alloy,the BNNP/ZK61 composites display simultaneous improvements in yield strength,hardness and ductility,achieving good strength-ductility *** research is expected to shed some light on BNNP potentials for designing and producing magnesium composites with high strength and good ductility.

关键词： BN nanoplatelet Magnesium composite Strength Ductility Spark plasma sintering Friction stir processing

Quasi-in-situ investigation into the microstructure and texture evolution of pure magnesium during friction stir welding

在线全文

学校读者我要写书评

暂无评论

Journal of Magnesium and Alloys 2020年第4期8卷 1071-1083页

作者： Zhou Mengran sun yufeng Morisada Yoshiaki Ushioda Kohsaku Fujii Hidetoshi Joining and Welding Research Institute Osaka UniversityOsaka 567-0047Japan The State Key Laboratory of Tribology Department of Mechanical EngineeringTsinghua UniversityBeijing 100084China School of materials science and engineering Zhengzhou UniversityZhengzhou 450001China

The quasi-in-situ microstructure and texture evolution along the real flow path of pure magnesium during friction stir welding were *** representative stages were involved from the base metal to the formation of the final stir *** material experienced compression,preheating,acceleration,deceleration,and subsequent annealing over the course of the welding process.A highly concentrated(0001)texture,denoted as''orientation convergence^,was initiated at the beginning of the acceleration stage(shearing deformation zone)in front of the *** continuous and discontinuous dynamic recrystallization occurred simultaneously in the stir zone,and continuous dynamic recrystallization was determined to be the primary recrystallization *** marker material morphology and EBSD data were used to elucidate the in-situ evolution of the shear direction and shear plane along with the real flow path.

关键词： Magnesium Friction stir welding Texture evolution Material flow EBSD

First-Principles Studies of Structural Evolutions in Cathode Materials LiMO_(2)(M=Co,Mn,Ni)

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2024年第10期41卷 129-136页

作者： yufeng sun Xin-Gao Gong Ji-Hui Yang Key Laboratory for Computational Physical Sciences(MOE) Department of PhysicsFudan UniversityShanghai 200433China Shanghai Qizhi Institution Shanghai 200232China

We explore the structural evolutions of stoichiometric LiMO_(2)using the first-principles calculations combined with the cluster expansion *** automatically obtain the ground state structures of the stoichiometric LiMO_(2)by just considering the cation orderings in the quasi rock-salt structures and the following structural relaxations due to both the atomic size mismatches and the Jahn–Teller *** point out that,on the one hand,the cation orderings are mainly determined by the nearest,the second nearest,and the third nearest cation interactions and can be obtained from the‘phase diagram’we have built using the relative strengths of effective cluster interaction(ECI).On the other hand,the structural relaxations are dominated by the crystal field splitting(CFS)energies,i.e.,structures with larger CFS energies are more *** calculating the ECIs and CFS energies for various structures of LiMO_(2),we clearly show how ECI and CFS play roles in determining the structural evolution mechanism of these systems.

关键词： method relaxation cluster

Microstructure and Mechanical Properties of Friction Stir Welded 1.5GPa Martensitic High-Strength Steel Plates

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2022年第7期35卷 1079-1089页

作者： Pengcheng Zhu Lin Zhang Zhaochang Li KHLo Jianfeng Wang yufeng sun Shaokang Guan School of Materials Science and Engineering Zhengzhou UniversityZhengzhou 450001China BAIC Group Off-Road Vehicle Co.Ltd Beijing 101300China Department of Electromechanical Engineering Faculty of Science and TechnologyUniversity of MacaoMacaoChina Henan Key Laboratory of Advanced Magnesium Alloys Zhengzhou 450002China

In this study, 2.4 mm thick high-strength martensitic steel plates with a tensile strength of 1500 MPa were friction stir welded at various welding speeds of 40, 60, 80, 100, 120 mm/min and a constant rotation speed of 300 rpm. Sound joints could be obtained when the welding speed was 40, 60 and 80 mm/min, while a kissing bond was found in the joint welded at 100 and 120 mm/min. It was revealed that the peak temperature exceeded A C3(the end temperature at which all ferrite transformed to austenite when the steel was heated) for all the welding conditions and martensitic structures were fi nally formed in the stir zone of the joints. A signifi cant decrease in hardness was located in the heat-aff ected zone, which had a transitional microstructure from tempered martensite near base metal to a mixed structure containing hard martensite, soft ferrite and bainite near stir zone. For the sound joints, the specimen was fractured in the heat-aff ected zone during tensile tests and the highest tensile strength could reach about 1058 MPa.

关键词： Martensitic steel Friction stir welding Heat-aff ected zone Microstructure Mechanical properties

Preparation of Biodegradable Mg/β-TCP Biofunctional Gradient Materials by Friction Stir Processing and Pulse Reverse Current Electrodeposition

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2020年第1期33卷 103-114页

作者： Yabo Zhang Huiling Yang Shaoqian Lei Shijie Zhu Jianfeng Wang yufeng sun Shaokang Guan School of Materials Science and Engineering Zhengzhou UniversityZhengzhou 450001China Henan Key Laboratory of Advanced Magnesium Alloys Zhengzhou 450002China

Mg alloys,as a new generation of biodegradable bone implant materials,are facing two tremendous challenges of enhancing strength and reducing degradation rate in physiological environment to meet clinical *** this study,tricalcium phosphate(β-TCP)particles were dispersed in Mg–2 Zn–0.46 Y–0.5 Nd alloy by friction stir processing(FSP)to produce Mg-based functional gradient materials(Mg/β-TCP FGM).On the surface of Mg/β-TCP FGM,the hydroxyapatite(HA)coating was prepared by *** effects of FSP and electrochemical parameter on the microstructure,microhardness,bonding strength and corrosion performance of the Mg/β-TCP FGM were *** four passes of FSP,a uniform and fine-grained structure was formed in Mg/β-TCP and the microhardness increased from 47.9 to 76.3 *** to the samples withoutβ-TCP,the bonding strength of the Mg/β-TCP FGM increased from 23.1±0.462 to 26.3±0.526 MPa and the addition of degradableβ-TCP contributed to the in situ growth of HA *** thickness of HA coating could be dominated by controlling the parameters of *** to the results of immersion tests and electrochemical tests in simulated body fluid,it indicated that the degradation rate of the Mg/β-TCP FGM could be adjusted.

关键词： Biodegradable magnesium alloy Biofunctional gradient materials Friction stir processing Tricalcium phosphate(β-TCP) Electrodeposition

Implementation and decoding method of OCC system based on MIMO

在线全文

学校读者我要写书评

暂无评论

Optoelectronics Letters 2022年第1期18卷 18-23页

作者： sun yufeng SHI Wenxiao SHAO Xinrui LIU Wei LIU Anqi Department of Communications Engineering Jilin UniversityChangchun 130012China

The application of high-frame-rate cameras as well as the complex image processing techniques will lead to a series of problems,such as high system cost and long transmission *** this paper,we introduce narrow-band filtering technology to reduce the impact of optical noise and reduce the complexity of image processing from the physical *** also introduce multiple-input multiple-output(MIMO)technology into the optical camera communication(OCC)system to increase system transmission rate,and propose a light emitting diode(LED)array decoding algorithm based on the directional projection method to reduce the system *** accumulating the target pixel values in each row and column of the image,the proposed method then determines the position and boundary of the detected target to distinguish the target area from the *** results indicate that the communication distance can reach up to 5.5 m without error bits *** the LED array at the transmitter of this system flashes at a frequency of 12 Hz,the transmission rate can reach 126.32 bit/s.

关键词： MIMO communication system

Initial micro-galvanic corrosion behavior between Mg_(2)Ca and α-Mg via quasi-in situ SEM approach and first-principles calculation

在线全文

学校读者我要写书评

暂无评论

Journal of Magnesium and Alloys 2023年第3期11卷 958-965页

作者： Chen Xu Jianfeng Wang Chen Chen Chao Wang yufeng sun Shijie Zhu Shaokang Guan School of Materials Science and Engineering Zhengzhou UniversityZhengzhou 450001China

The initial micro-galvanic corrosion behavior of Mg-30wt%Ca alloy only containing Mg_(2)Ca andα-Mg was studied by immersion testing in a 0.9%Na Cl solution at 37°*** quasi-in situ SEM and TEM results show that Mg_(2)Ca corroded easier thanα-Mg,indicating that Mg_(2)Ca acted as an *** work function(Φ)for Mg_(2)Ca calculated by first-principles is significantly lower compared to that forα-*** Volta potential measured by a scanning Kelvin probe force microscope reveals that the Mg_(2)Ca had a relatively low Volta potential(ψ)*** lowerΦandψvalues for Mg_(2)Ca indicate a lower electrochemical nobility,which is consistent with the experimental phenomenon.

关键词： Magnesium alloy Quasi-in situ SEM Galvanic corrosion First-principles calculations Work function Volta potential