LUO Zhiping
,
ZHANG Shaoqing
,
SONG DeyuBeijing Institute of Aeronoutical Materials
,
Beijing
,
100095
,
ChinaTANG Yali
,
ZHAO DongshanZhengzhou Institute of Technology
,
Zhengzhou
,
450002
,
China Manuscript received
,
27 April 1994
金属学报(英文版)
In the as-cast Mg-Zn-Zr-Y alloys, the quasicrystal phases show massive and eutectoid plate morphologies. The selected area dijfraction(SAD) revealed that a large pan of the quasicrystals are face-centered icosahedral (FCI), while a small amout of the quasicrystals belong to the simple icosahedral (SI) phase. It was found that in homogenized alloys, a part of the grain boundry phases was dissolved,and small massive W-phase and lath-shape MgZn_(2) phase dispersedly precipitate in the grains. The transformation of the quasicrystals relates to the temperature. After homogenizing at 360 ℃ , the quasicrystals still present, while after homogenizing at 400 ℃ , the quasicrystals transformed into a new C-type orthorhombic phase witha = 0.975 nm, b = 1.137nm and=0.935 nm.
关键词:
Mg-Zn-Zr-Y alloy
,
null
,
null
Materials Science & Engineering C-Biomimetic Materials Sensors and Systems
The terminology of materials study inspired by biological systems or phenomena is analyzed at first. It is pointed that the term "bio-inspired" may be better than the terms "bionic" or "biomimetic", since the former is relatively easy to be accepted. The new trends of bio-inspired study of structural materials are analyzed in short. Some progress in bio-inspired design and processing of materials in this institute (IMRCAS) are summarized briefly in this talk, such as biomimetic design of worst bonding interface for composites; dumbell-like whiskers simulating animal bone; fractal tree reinforcement by mimicry of branched roots in soil; etc. The possibility of modification and recovery of materials by nonequilibrium bio-inspired treatment are further explored, including the nonequilibrium process under transient heating, dissipative structure and self-organization process of open system, inspiration by living process, influence of high intensive electropulsing on the working Life of materials, a possible way of fatigue recovery of materials and the healing effect of electropulsing in metals. Some tentative practice in biomaterial modification are also studied such as the reformed bamboo reinforced aluminium laminates, etc. A discussion on the methodology of bio-inspired study of materials consists briefly in the last part of the talk. (C) 2000 Elsevier Science S.A. All rights reserved.
关键词:
bio-inspired;bionic;biomimetic;structural materials;composites
Journal of Applied Physics
The dependence of yield strength, uniform elongation, and toughness on grain size in metallic structural materials was discussed. The toughness is defined as the product of yield strength and uniform elongation. The yield strength versus grain size can be well described by the Hall-Petch relation; however, the uniform elongation versus grain size is not well understood yet. A simple model involving the densities of geometrically necessary dislocations and statistically stored dislocations was proposed to estimate the uniform elongation versus grain size. Existing data for low carbon steels and aluminum indicate that, in the grain size less than 1 mu m, the materials usually exhibit high strength and low uniform elongation and, in the grain size greater than 10 mu m, the materials usually exhibit low strength and high elongation; in either case the toughness is low. However, in the grain size of several micrometers, the toughness is the highest. It is suggested that we should pay more attention to develop the metallic materials with grain size of several micrometers for structural applications. (c) 2007 American Institute of Physics.
关键词:
nanocrystalline copper;nanostructured metal;steels;deformation;ductility;law
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
,
null
,
null
,
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
Progress in Chemistry
Hydrogen storage is a key to the utility of hydrogen as a renewable energy source The encapsulation of hydrogen on porous materials has its special advantages In this review, the fundamentals of the encapsulation are briefly introduced The relevant porous materials of zeolites, metal coordination compounds, hollow glass microspheres, fullerenes and their derivative, and their characteristics on encapsulation of hydrogen are addressed in details Recent progresses on the studies of the encapsulation of hydrogen on porous materials are summarized The differences between the encapsulation and physical adsorption of hydrogen on porous materials are analyzed based on their required operation conditions, material specifications and energy barriers Finally, the perspectives of the applications and further studies on the encapsulation of hydrogen are discussed
关键词:
hydrogen storage;encapsulation;porous materials;molecular-orbital calculations;hollow glass microspheres;boron-nitride;fullerene;diffusion;zeolites;carbon;gases;frameworks;sodalite
