材料期刊网

CARBIDE PRECIPITATION AND BAINITE TRANSFORMATION IN Fe-C-Si ALLOY

R.L. Zuo , L. Fang and P. D. Ding(Department of Metallurgy and Materials Engineering , Chongqing University , Chongqing 630044 , China)

金属学报(英文版)

The upper bainite formed isothermally at 480℃ C in Fe-0. 38C-1. 73Si alloy was studied by using transmission electron microscopy (TEM). It was found by electron diffraction and crystallographic analysis that bainitic carbide precipitation originated from bainitic ferrite (BF), in which the initial supersaturation did not come up to the average carbon content of the alloy. It is suggested that bainite transformation in steel should be a coupled process of transformation dislocation movement controlled by carbon diffusion in austenite.

关键词: : bainite , null , null , null

Department of Metallurgy and Materials Engineering of Chongqing University

YAN Guangting Chongqing University , Sichuan , China.

材料科学技术（英文）

关键词:

Service Performance of Engineering Materials

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

Biomimicry of bamboo bast fiber with engineering composite materials

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

Strengthening Materials by Engineering Coherent Internal Boundaries at the Nanoscale

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

STATISTICAL EVALUATION OF CRITICAL INCLUSION FACTOR FOR SECONDARY RECRYSTALLIZATON IN 3%Si STEEL Lecturer,Department of Materials Engineering,Southwestern Jiaotong University,Chengdu 610031,China

LI Shuchen Southwestern Jiaotong University , Chengdu , ChinaCHEN Mengzhe KE Jun University of Science and Technology Beijing , Beijing , China

金属学报(英文版)

On the basis of statistical data of MnS in the conventional 3% Si steel sheeets after various annealing processes,the critical inclusion factor has been evaluated to be 20 mm~(-1).The inhi- bition of MnS to grain growth has been exactly described.

关键词: 3%Si steel , null , null

Brief Outline of the Metallurgy Department of Kunming Institute of Technology

LIU Chunpeng Kunming Institute of Technology , Kunming 650093 , China.

材料科学技术（英文）

关键词:

Fe2+对嗜铁钩端螺旋菌L. ferriphilum生长活性的影响

高健 , 康健 , 吴学玲 , 徐競 , 李邦梅 , 邱冠周

中国有色金属学报

以分离于江西某铜矿的嗜铁钩端螺旋菌(L. ferriphilum YSK)菌株为研究对象,报道不同Fe2+浓度对 L. ferriphilum生长活性的影响.结果表明,YSK菌株生长最适宜的Fe2+浓度约为0.1 mol/L.当初始Fe2+浓度为0.4 mol/L时,进入对数生长期前很明显需要一个较长的延迟期,表明该Fe2+浓度对细胞的生长产生较强的抑制作用;当初始Fe2+浓度为0.6 mol/L时,YSK菌株的生长完全受到抑制.尽管高浓度的Fe2+抑制细胞的生长,但受到抑制而不生长繁殖的YSK细胞仍然具有氧化Fe2+的能力.

关键词: L.ferriphilum YSK菌株 , Fe2+ , 生长活性

R & D ACTIVITIES ON AEROSPACE MATERIALS IN KOREA

H.M. Kim(Korea Institute of Machinery and Materials , Korea Manuscript received 26 August 1996)

金属学报(英文版)

This paper briefly reviews research and development programs in Korean aerospace industry,with an emphasis on aircraft materials technology. International collaborations in these areas are outlined and the R & D activities are highlighted against the　background of the national economy.It is shown that the investment from government agencies and large enterprises has led to healthy development of aerospace materials industries in Korea.

关键词: :R & D , null , null , null

Experimental and modeling investigation on SiC(p) distribution in powder metallurgy processed SiC(p)/2024 Al composites

Materials Science and Engineering a-Structural Materials Properties Microstructure and Processing

SiC(p)/2024Al composites were fabricated through the powder metallurgy (PM) technique. The mixing process was modified by using a high ball to charge ratio (BCR), which resulted in improved homogeneity of the SiC(p) distribution, as well as enhanced tensile strengths of the as-pressed composites. A small particle size ratio of aluminum to SiC(p) (PSR) and extrusion also improved the uniformity of the SiC(p) distribution. The improvements by the three approaches were quantitatively analyzed using a critical volume fraction model. The model demonstrates that a small PSR and a large deformation ratio of aluminum particles were two essential factors of improving the homogeneity of the SiC(p). A homogeneity analysis using the Dirichlet Tessellation method provided an additional explanation for the model. Crown Copyright (C) 2010 Published by Elsevier B.V. All rights reserved.

关键词: Analytical modeling;Metal-matrix composites;Powder metallurgy;Reinforcement distribution;aluminum-matrix composites;particle-size ratio;mechanical-properties;microstructure;reinforcement