检索结果-南通市图书馆

Grain-size effect on dislocation source-limited hardening and ductilization in bulk pure Ni

在线全文

学校读者我要写书评

暂无评论

Journal of Materials science & Technology 2023年第23期154卷 9-21页

作者： Kai Hu Jun Yi Bo Huang Gang Wang institute of Materials School of Materials Science and Engineering Shanghai University Shanghai 200444 China

Dislocation source-limited hardening and ductilization is an effective strategy to obtain superior strength-ductility synergy in some engineering structural metals. Recent works demonstrated that the synergy could be enhanced by grain-size reduction. However, the mechanism of grain-size dependence is still a mystery. In this work, bulk pure Ni produced by electrodeposition and subsequent annealing, with grain sizes ranging from ∼20 nm to ∼20 µm, were methodically investigated to unravel the mechanism of the grain-size effect on dislocation source-limited hardening and ductilization. The high-density nano-twinning in the as-electrodeposited nanograined specimens exhibited better thermodynamic stability than the peers with random high-angle grain boundaries, leading to fine recrystallized grains with low-density dislocations. The low dislocation density enabled extra hardening beyond grain boundary strengthening via yield-point behavior with grain sizes ranging from ∼110 nm to ∼10 µm and extra ductilization over ∼500 nm. This work demonstrated that the prerequisite for dislocation source-limited hardening was that the dislocation density of the specimen should be lower than the size-dependent critical value of ((1.1 × 107 /d ) m^(–2), d is the grain size in unit of the meter) where a transition from forest-dominated hardening to dislocation source-limited hardening could occur. On the other hand, dislocation source-limited ductilization only worked when the grain size was comparable to/larger than the theoretical dislocation mean slip distance. Dislocation source-limited ductilization resulted from more room in grains for accumulation of dislocations and deformation nano-stacking faults enabling the higher work hardening rate. This work offered an altogether new avenue to obtain stronger and more ductile metallic materials through utilizing grain-size dependent dislocation source-limited hardening and ductilization.

关键词： Dislocation source-limited hardening Dislocation source-limited ductilization Grain size Yield point Hall-Petch slope

Microstructure and Tensile Properties of a Nb–Mo Microalloyed 6.5Mn Alloy Processed by Intercritical Annealing and Quenching and Partitioning

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

Acta Metallurgica Sinica(English Letters) 2017年第7期30卷 665-674页

作者： Ming-Hui Cai Hong-Shou Huang Hai-Jun Pan Sheng-Hui Sun Hua Ding Peter Hodgson school of Materials science and Engineering Northeastern University institute for Frontier Materials Deakin University

The transformation behavior, microstructural evolution and mechanical properties were compared in a coldrolled Nb–Mo microalloyed 6.5Mn alloy after intercritical annealing（IA） and quenching and partitioning（Q ＆ P）,respectively. The thermodynamic calculation and theoretical analysis were used to determine the optimal heat treatment parameters. The Q ＆ P samples exhibited relatively higher strength with relatively low ductility, mainly due to the hard martensite matrix, which resulted in continuous yielding behavior upon loading, whereas the IA samples showed the significantly improved ductility, which benefited from the more sufficient transformation-induced plasticity（TRIP） effects and the softer ultrafine ferrite matrix. The dependence of yield point elongation（YPE） of IA samples on grain size demonstrated that the YPE value was in the reverse proportional relationship to the average grain size, which agreed well with theoretical analysis.

关键词： Medium Mn steel Intercritical annealing Quenching and partitioning Mechanical properties TRIP effect Yield point elongation

Effect of thickness and grain size on material behavior in micro-bending

在线全文

学校读者我要写书评

暂无评论

Transactions of Nonferrous Metals Society of China 2009年第S02期19卷 507-510页

作者： SHAN De-bin WANG Chun-ju GUO Bin WANG Xin-wei school of Materials science and Engineering Harbin Institute of TechnologyHarbin 150001China

Micro-bending tests were performed to investigate effects of thickness and grain size on material behavior in sheet metal *** rolling brass C2680 foil was selected as the experimental material,and it was annealed to eliminate the work-hardening and get different grain sizes.A device was specially designed for three-point bending with two load *** results show that the bending force increases with increasing the punch *** the foil of same thickness,a smaller punch radius leads to a larger bending *** the grain size increases,the bending force becomes *** effects are observed *** results have been analyzed by work-hardening,Hall-Petch equation and free surface effect.

关键词： micro-forming micro-bending size effects free surface effect

Design and application of copper/lithium composite anodes for advanced lithium metal batteries

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2024年第3期43卷 942-970页

作者： Bin Zhang Ji-Ping Ma Yang Zhao Tong Li Jin-Lin Yang Zhan-Ling Zhang Shi-Zhong Wei Guang-Min Zhou school of Materials science and Engineering Henan University of Science and TechnologyLuoyang 471003China Shenzhen Geim Graphene Center Tsinghua Shenzhen International Graduate SchoolTsinghua UniversityShenzhen 518055China school of Physical and mathematical sciences Nanyang Technological UniversitySingapore 637371Singapore Shenzhen Geim Graphene Center Tsinghua-Berkeley Shenzhen InstituteTsinghua Shenzhen International Graduate SchoolTsinghua UniversityShenzhen 518055China

Lithium(Li)is a promising candidate for nextgeneration battery anode due to its high theoretical specific capacity and low reduction ***,safety issues derived from the uncontrolled growth of Li dendrite and huge volume change of Li hinder its practical application.C onstructing dendrite-free composite Li anodes can significantly alleviate the above ***(Cu)-based materials have bee n widely used as substrates of the composite electrodes due to their chemical stability,excellent conductivity,and good mechanical ***/lithium(Cu/Li)composite anodes significantly regulate the local current density and decrease Li nucleation overp otential,realizing the uniform and dendrite-free Li *** this review,Cu/Li composite methods including electrodeposition,melting infusion,and mechanical rolling are systematically summarized and ***,design strategies of Cu-based current collectors for high performance Cu/Li composite anodes are *** challenges and future development for Cu/Li composite anodes are presented and *** hope that this review can provide a comprehensive understanding of Cu/Li composite methods of the latest development of Li metal anode and stimulate more research in the future.

关键词： Lithium metal batteries Cu/Li composite anode Electrodeposition Thermal melting infusion Mechanical rolling

Process optimization diagram based on FEM simulation for extrusion of AZ31 profile

在线全文

学校读者我要写书评

暂无评论

中国有色金属学会会刊：英文版 2008年第A01期18卷 247-251页

作者：刘钢周捷 J DUSZCZYK school of Materials science and Engineering Harbin Institute of Technology Department of Materials science and Engineering Delft University of Technology

The ram speed and the billet temperature are the primary process variables that determine the quality of the extruded magnesium profile and the productivity of the extrusion *** optimization of the extrusion process concerns the interplay between these two variables in relation to the extrudate temperature and the peak extrusion *** 3D computer simulations were performed to determine the effects of the ram speed and the billet temperature on the extrudate temperature and the peak extrusion pressure,thereby providing guidelines for the process optimization and minimizing the number of trial extrusion runs needed for the process optimization.A case study on the extrusion of an AZ31 X-shaped profile was *** correlations between the process variables and the response from the deformed material,extrudate temperature and peak extrusion pressure,were established from the 3D FEM simulations and verified by the *** research opens up a way to rational selection of the process variables for ensured quality and maximum productivity of the magnesium extrusion.

关键词： AZ31镁合金工艺过程最佳化有限元分析

Integrating local and partial network view for routing on scale-free networks

在线全文

学校读者我要写书评

暂无评论

science China(Information sciences) 2013年第10期56卷 117-126页

作者： TANG MingDong ZHANG GuoQiang SUN Yi LIU JianXun YANG Jing LIN Tao Key Lab of Knowledge Processing and Networked Manufacturing Hunan University of Science and Technology school of Computer science and Technology Nanjing Normal University institute of Computing Technology Chinese Academy of Sciences China Mobile research institute institute of Acoustics Chinese Academy of Sciences

Traditional routing schemes,such as OSPF,optimize data plane routing efciency by maintaining full view of the network at the control ***,maintaining full network view and handling frequent routing information updates are costly in large-scale complex networks,which are considered to be the root causes for the routing scalability ***,it is suggested that routing on local or partial information is plausible if slight performance degradation is *** paper proposes a routing scheme,operating on an integrated network view at each node that consists of its local neighborhood and a globally unique skeleton *** scheme signifcantly reduces storage,communication and processing *** scale-free networks,this beneft only comes at the cost of marginal performance degradation,which implies that it is not worthwhile to do shortest path routing based on full view of the network on scale-free *** contrast,the routing efciency is severely aggravated on purely random networks,indicating the inappropriateness of this scheme and the rationality of maintaining full network view on random networks.

关键词： routing scale-free networks complex networks power-law

Electronic structure and properties of LaNi_5 compound from first principles

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Rare Metals 2010年第4期29卷 351-354页

作者： WU Yeqiong YAN Mufu school of Materials science and Engineering Harbin Institute of Technology Harbin 150001 China

The energy, electronic structure, and magnetic and mechanical properties of LaNi5 compound have been studied by the first-principles method based on the density functional theory. The results show that the calculated lattice parameters of LaNi5 compound are almost the same with the experimental ones, and the compound is easy to form and very stable. The bond between La and Nil atoms is an ionic bond, and electrostatic attraction effect exists between Ni atoms. The farther the distance between Ni atoms in the LaNi5 crystal cell is, the stronger the electrostatic attraction effect is. LaNi5 intermetallic compound is ductile and ferromagnetic. The calculated hardness value of LaNi5 compound is 7.04 GPa, and the calculated elastic properties are close to the experimental results.

关键词： LaNi5 mechancal properties first-pincioles electronic structure

Topo semantic constraint-violations in spatial database

在线全文

学校读者我要写书评

暂无评论

Journal of Harbin institute of Technology(New Series) 2008年第4期15卷 506-512页

作者：凯龙李香刘宏伟杨孝宗 school of Computer science and Technology Harbin Institute of Technology school of Computer science and Technology Harbin Engineering University

Aiming at the problem that current geographical information systems(GIS)usually does not maintain semantic and user-defined constraints out of three consistency-constrains(third refers to topology constraint),this research focuses on building an efficient spatial data management system using two constraint violation detection *** algorithm for constraint violation detection has been derived to maintain the error-free up-to-date spatial *** indicate that the developed constraint violation detection(CVD)system is more efficient compared with conventional systems.

关键词： topo-semantic constraint rule constraint violation spatial object spatial database R-tree GIS

Using Small Punch Test to Investigate the Mechanical Properties of X42 Exposed to Gaseous Hydrogen:Effect of Pressure,Pre-charge Time,Punch Velocity and Oxygen Content

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2024年第11期37卷 1961-1983页

作者： Hu-Yue Wang Hong-Liang Ming Dong-Ceng Hou Jian-Qiu Wang Wei Ke En-Hou Han school of Materials science and Engineering Northeastern UniversityShenyang110819China CAS Key Laboratory of Nuclear Materials and Safety Assessment Institute of Metal ResearchChinese Academy of SciencesShenyang110016China Analysis and Test Center Institute of Metal ResearchChinese Academy of SciencesShenyang110016China institute of Corrosion science and Technology Guangzhou510530China

This study investigated the effect of pressure,pre-charge time,punch velocity and oxygen content on the mechanical properties of X42 pipeline steel in gaseous hydrogen environment by using small punch *** exposed to nitrogen,the fracture mode of X42 pipeline steel undergoes ductile fracture,but in the presence of hydrogen,it shifts to brittle ***,an increase in hydrogen pressure or a decrease in punch velocity is found to enhance the hydrogen embrittlement susceptibility of X42 pipeline steel,as evidenced by the decrease of maximal load,displacement at failure onset and small punch *** the effect of pre-charge time on the hydrogen embrittlement susceptibility of X42 pipeline steel is not very ***,the presence of oxygen has been found to effectively inhibit hydrogen *** the oxygen content in hydrogen increases,the hydrogen embrittlement susceptibility of X42 pipeline steel decreases.

关键词： X42 pipeline steel Hydrogen embrittlement Mechanical properties Scanning electron microscopy(SEM) Small punch test