CHAI Huifen RUAN Zheng FAN Quncheng (Xi'an Jiaotong University
,
Xi'an
,
China CHAI Huifen
,
associate professor
,
Department of Materials
,
Xi'an Jiaotong University
,
Xi'an 710049
,
China
金属学报(英文版)
The cyclic behaviours of two prestrained materials with different slip modes have been com- pared.From the analysis of hysterisis loops,it is suggested that the decrease in back stress dominates the cyclic process of Cu-Zn alloy with planar slip mode,while the decrease in frictional stress is the main factor affecting the behaviour of Cu with wavy slip mode.The re- lation between the dislocation configuration and internal stress has been also discussed.By means of the relation just mentioned,the variations of dislocation configuration before and after fatigue of the two materials,the differences in their softening mechanism and mechani- cal behaviour could be interpreted.
关键词:
slip mode
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null
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null
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FU Changpu HAN Yong
,
L(?) Shuangyun AN Yunzheng Shaanxi Mechanical Engineering Institute
,
Xi'an
,
ChinaPAN Jingda DU Wenfeng Beijing Heavy Electric Machine Works
,
China associate professor
,
Department of Materials
,
Shaanxi Mechanical Engineering Institute
,
Xi'an 710048
,
China
金属学报(英文版)
Studies were made of the creep properties and structure change of steet 20Cr11MoVNbNB at 550-650℃.It is found that at 550℃ when creep stress>180 MPa there exists linear rela- tion with two different slopes β_1 and β-2 between transitional creep strain ε_β and creep time t~(1/3),and β_1(in initiol period)>β_2(in later period).The Creep rate of stable stage at 550℃ can be expressed by =Aσ exp(-Q_ /RT),where,n=4.7.A exp(-Q_ /RT)= 5.37×10~(-16).Apparent creep activation energy Q_ =430 kJ/mol at 550-650℃,which is much higher than the self-diffusion activation energy of atoms for matrix Fe.In creep process,as the creep stress and time increase,the total weight of precipitated phases and rela- tive weight of Cr,Mo and V increase,but those of Fe and Nb decrease in precipitated phases,
关键词:
20Cr11MoVNbNB
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null
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null
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null
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LIU Jian QIU Baoqin LIU Muyi XIAO Yaofu University of Science and Technology Beijing
,
Beijing
,
China associate professor
,
Department of Materials
,
University of Science and Technology Beijing
,
Beijing 100083
,
China
金属学报(英文版)
The phase constitution and variation of Nd_(14)Fe_(73)Co_6B_7 alloy after hydriding and subsequent dehydriding treatment at 770℃ have been investigated respectively by means of X-ray diffraction,SEM,TEM and magnetic measurement techniques.The original coarse,as cast grain structure,is dissolved into α-Fe,Nd hydride and Fe_2B mixture with average dimension of 0.1 μm,during hydriding process,and subsequently the triphase mixture recombined into finely unique Nd_2Fe_(14)B phase with dimension of 0.3 μm by desorbing the hydrogen.It was found that the Nd-rich phase distributed at the boundary of as-cast grain structure diffused into matrix Nd_2Fe_(14)B grain during hydriding.It remains during dehydriding and distribute homogeneously around some colonies composed of fine grains of Nd_2Fe_(14)B.
关键词:
Nd_(14)Fe_(73)Co_6B_7
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null
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null
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QIAO Lijie LIU Rui XIAO Jimei University of Science and Technology Beijing
,
Beijing
,
China
金属学报(英文版)
The effects of stress components on nucleation sites and propagation directions of stress cor- rosion cracks in brass were investigated with specimens under mode Ⅱ and mode Ⅲ loadings. The results indicated that under mode Ⅱ loading,stress corrosion cracks nucleated on the site with maximum normal stress component and propagated along the plane perpendieular to the maximum normal stress,under mode Ⅲ loading,the stress corrosion crack was not evident on the 45°plane due to the general corrosion in aqueous solution with high NH_4OH concentra- tion,while stress corroded in aqueous solution with low NH_4OH concentration, numerous cracks with spacings of 10—150μm were found on the 45°plane with maximum normal stress and no stress corrosion cracks was observed on the plane with maximum shear stress.
关键词:
stress corrosion cracking
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null
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null
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Advanced Materials
Popularization of portable electronics and electric vehicles worldwide stimulates the development of energy storage devices, such as batteries and supercapacitors, toward higher power density and energy density, which significantly depends upon the advancement of new materials used in these devices. Moreover, energy storage materials play a key role in efficient, clean, and versatile use of energy, and are crucial for the exploitation of renewable energy. Therefore, energy storage materials cover a wide range of materials and have been receiving intensive attention from research and development to industrialization. In this Review, firstly a general introduction is given to several typical energy storage systems, including thermal, mechanical, electromagnetic, hydrogen, and electrochemical energy storage. Then the current status of high-performance hydrogen storage materials for on-board applications and electrochemical energy storage materials for lithium-ion batteries and supercapacitors is introduced in detail. The strategies for developing these advanced energy storage materials, including nanostructuring nano-/microcombination, hybridization, pore-structure control, configuration design, surface modification, and composition optimization, are discussed. Finally, the future trends and prospects in the development of advanced energy storage materials are highlighted.
关键词:
lithium-ion batteries;carbon nanotube electrodes;enhanced hydrogen;storage;metal-organic frameworks;double-layer capacitors;n-h system;carbide-derived carbons;ammonia borane dehydrogenation;ordered;mesoporous carbons;high-rate performance
LIU Guoquan Department of Materials Science and Engineering
,
University of Science and Technology Beijing
,
100083
,
China.
材料科学技术（英文）
Quantitative analysis of populations having a geometric structure,which has developed into a special scientific subject called microstructology or stereology,is of great importance to the characterization and evaluation of microstructures and their evolution in various processes.This paper, besides a brief discussion on those topics such as the recent developments of computer assisted image analysis,mathematical morphology,and fractal analysis,will mainly focus on the scope,fundamen- tals,present status,and perspectives of classical stereology.Several case examples of its application to materials science will also be given.
关键词:
stereology
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null
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null
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null
CAI Jiuju
,
LU Zhongwu
,
YUE Qiang
钢铁研究学报(英文版)
The industrial system should learn from the natural ecosystem. The resource utilization efficiency should be increased and the environmental load should be decreased, depending on the materials recycled in the system. The classification of industrial materials from the viewpoint of largescale recycling was stated. Recycling of materials, on three different levels, was introduced in the industrial system. The metal flow diagram in the life cycle of products, in the case of no materials recycled, materials partially recycled, and materials completely recycled, was given. The natural resource conservation and the waste emission reduction were analyzed under the condition of materials completely recycled. The expressions for the relation between resource efficiency and material recycling rate, and the relation between ecoefficiency and material recycling rate were derived, and the curves describing the relationship between them were protracted. The diagram of iron flow in the life cycle of iron and steel products in China, in 2001, was given, and the iron resource efficiency, material recycling rate, and iron ecoefficiency were analyzed. The variation of iron resource efficiency with the material recycling rate was analyzed for two different production ratios.
关键词:
recycling;industrial material;product life cycle;resource efficiency;ecoefficiency;material recycling rate
