Z.K. Fan
,
Y.Q. Wang
,
S.H. Liangand HS. Huang(School of Materials Science and Engineering
,
Xi'an University of Technology
,
Xi'an 710048
,
China)(Mechanical Engineering Department
,
Tsinghua University
,
Beijing 100084
,
China)
金属学报(英文版)
The combinational use of alloying elements with positive and negative segmpation hasbeen shown to be very thective in strengthening the matrix of cast iron. Negativesegmpation alloying elements, Cu and Si, make the inner parts of dendritic austenitesand eutectic cells get good handenability. On the contrury, positive segmpation alloyingelements Cr and Mn make the outer parts of dendrites have higher microhaofness.Appropriate combination of the above two tyPes Of alloying elements can produce auniform microharkness and high strength in grny cast irons.
关键词:
cast iron
,
null
,
null
Andrej Atrens
材料科学技术（英文）
Corrosion research by Atrens and co-workers has made significant contributions to the understanding of the service performance of engineering materials. This includes: (1) elucidated corrosion mechanisms of Mg alloys, stainless steels and Cu alloys, (2) developed an improved understanding of passivity in stainless steels and binary alloys such as Fe-Cr, Ni-Cr, Co-Cr, Fe-Ti, and Fe-Si, (3) developed an improved understanding of the melt spinning of Cu alloys, and (4) elucidated mechanisms of environment assisted fracture (EAF) of steels and Zr alloys. This paper summarises contributions in the following: (1) intergranular stress corrosion cracking of pipeline steels, (2) atmospheric corrosion and patination of Cu, (3) corrosion of Mg alloys, and (4) transgranular stress corrosion cracking of rock bolts.
关键词:
Stress corrosion cracking
,
null
,
null
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
Materials Science & Engineering C-Biomimetic Materials Sensors and Systems
Bamboo, one of the strongest natural structural composite materials, has many distinguishing features. It has been found that its reinforcement unit, hollow, multilayered and spirally-wound bast fiber, plays an extremely important role in its mechanical behavior. In the present work, on the basis of the study on bamboo bast fiber and wood tracheid, a biomimetic model of the reinforcing element, composed of two layers of helically wound fiber, was suggested. To detect the structural characteristics of such a microstructure, four types of macro fiber specimens made of engineering composites were employed: axially aligned solid and hollow cylinders, and single- and double-helical hollow cylinders. These specimens were subjected to several possible loadings, and the experimental results reveal that only the double-helical structural unit possesses the optimum comprehensive mechanical properties. An interlaminar transition zone model imitating bamboo bast fiber was proposed and was verified by engineering composite materials. In our work, the transition zone can increase the interlaminar shear strength of the composite materials by about 15%. These biomimetic structural models can be applied in the design and manufacture of engineering composite materials.
关键词:
bamboo;bast fiber;biomimetics;engineering composites
Science
Strengthening materials traditionally involves the controlled creation of internal defects and boundaries so as to obstruct dislocation motion. Such strategies invariably compromise ductility, the ability of the material to deform, stretch, or change shape permanently without breaking. Here, we outline an approach to optimize strength and ductility by identifying three essential structural characteristics for boundaries: coherency with surrounding matrix, thermal and mechanical stability, and smallest feature size finer than 100 nanometers. We assess current understanding of strengthening and propose a methodology for engineering coherent, nanoscale internal boundaries, specifically those involving nanoscale twin boundaries. Additionally, we discuss perspectives on strengthening and preserving ductility, along with potential applications for improving failure tolerance, electrical conductivity, and resistance to electromigration.
关键词:
strain-rate sensitivity;stacking-fault energy;nano-scale twins;cu-al;alloys;nanocrystalline metals;mechanical-properties;activation;volume;copper;deformation;behavior
刘公召
,
杨振声
,
张艳
,
邱克强
腐蚀与防护
doi:10.11973/fsyfh-201603002
采用失重法、电化学测试法,并结合扫描电镜和原子力显微镜观察,研究了在50℃条件下,N-(2-辛基-2咪唑啉)三亚乙基四酰胺(咪唑啉酰胺)分别在HCl/NH4Cl-H2O和H2S/NH4HS-H2O体系中对碳钢的缓蚀性能.结果表明:N-(2-辛基-2咪唑啉)三亚乙基四酰胺加量为15 mg/L时,缓蚀率接近90％,缓蚀效果明显;该缓蚀剂为抑制阳极型缓蚀剂,溶液中加入缓蚀剂后,碳钢试样形成较长的钝化区间,交流阻抗半径大,腐蚀电流明显减小.形貌观察显示N-(2-辛基-2咪唑啉)三亚乙基四酰胺能够在碳钢表面形成致密的保护膜.
关键词:
缓蚀性能
,
HCl/NH4Cl
,
H2S/NH4HS
,
保护膜
Douxing LI and Hengqiang YE (Laboratory of Atomic imaging of Solids
,
Institute of Metal Research
,
Chinese Academy of Sciences
,
Shenyang
,
110015
,
China)
材料科学技术（英文）
The present paper summarizes the current status of high resolution electron microscopy (HREM)and the applications of HREM to materials science and condensed matter physics. This review recounts the latest development of high resolution electron microscope, progress of HREM and the applications of HREM, including the crystal structure determination of microcrystalline materials and characterization of the local structure of the defects and nanostructured materials as well as qualitative and quantitative analysis of the grain boundaries, interfaces and interfacial reactions in the advanced materials by means of HREM in combination with electron diffraction,subnanometer level analysis, image simulation and image processing.
关键词:
N.V.Ch
,
ra Shekar
,
P.Ch.Sahu
,
K.Govinda Rajan
材料科学技术（英文）
Laser-heated diamond-anvil cell (LHDAC) is emerging as the most suitable, economical and versatile tool for the measurement of a large spectrum of physical properties of materials under extreme pressure and temperature conditions. In this review, the recent developments in the instrumentation, pressure and temperature measurement techniques, results of experimental investigations from the literature were discussed. Also, the future scope of the technique in various avenues of science was explored.
关键词:
Laser heating
,
null
,
null
,
null
Corrosion Science
The effect of Cl- ion on the anodic dissolution of iron in H2SO4 solutions containing low H2S level has been studied by electrochemical polarization curve measurements. The total energy and binding energy of the competitive adsorption for Cl- and HS- ions have been calculated with CNDO/2 method, as well as the net charge distribution of iron atoms at an anodic potential. The results showed that certain concentration of Cl- ion inhibit the anodic reaction of iron accelerated by HS-. However, when Cl- ion reached saturated adsorption, it began to promote the anodic reaction of iron due to the increased negative charge of iron atoms. (C) 1999 Elsevier Science Ltd. All rights reserved.
关键词:
iron;polarization;quantum chemistry;acid corrosion;anodic;dissolution;chloride solutions;kinetics
