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BEHAVIOUR OF INITIATION AND GROWTH OF SHORT FATIGUE CRACKS

WU Zhixue , XU Hao(Institute of Mechanical Engineering , Northeastern University , Shenyang 110006 , China)(Fushun Petroleum institute , Fushun 113001.China).(State Key Laboratory for Fatigue and Fracture of Materials , Institute of Metal Research , Chinese Academy of Sciences , Shenyang 110015 , China) Manuscript received 2 July 1995

金属学报(英文版)

Rotary bending fatigue tests were carried out using smooth specimens of a medium-carbon steel with two different grain sizes.The process of early crack development was observed by the replica method,and the effects of grain size and microstructure on short crack development were studied.It was shown that the initiation process of fatigue cracks is that the damaged region is intensified gradually,and the growth of short cracks relates to the coalescence of cracks.The grain size and microstructure have a great influence upon the initiation and growth of short cracks.A reasonable definition was given in relation to short fatigue crack initiation and propagation.

关键词: :fatigue damage , null , null , null

Guangzhou Institute of Energy Conversion,The Chinese Academy of Sciences,Guangzhou 510070,China

B.W. Wang , H. Shen

金属学报(英文版)

Ni-Cr System solar selective thin solid films were prepared by d.c. magnetron reactivesputtering under the atmosphere of O2 and N2. Ni-Cr alloy was chosen as targetmaterial and copper sheets as substrate. Using SEM, Spectrophotometer and Talystepto analyze the relations between the selective characteristic and the structure, theformation and the thickness of the thin films. The aim is to obtain good solar selectivethin films with high absorptance and low emittance, which is applied to flat plate solarheat collectors.

关键词: solar selective thin film , null , null , null

The effect of grinding on the sintering of raw petroleum coke

Carbon

Preparation of dense carbon materials without use of any binder was attempted, effect of grinding treatment on the characteristics of raw petroleum needle coke and on the properties of the sintered carbon compacts was investigated, and the sintering mechanizm of the coke after grinding was discussed. It was found that the coke particle size and crystalline size was decreased and the specific surface area of the coke was increased with grinding, and the influence was obvious up to 20 hours grinding treatment. The interlayer spacing of the coke after graphitization at 2773 K was gradually increased and the a-axis constant was marginally reduced with the grinding time. Results from the sintering experiment show that carbon materials can be sintered from the ground coke, and the density and flexural strength of the sintering compacts reached stable values of 1.8 g cm(-3) and about 70 MPa, respectively, after 20 hours grinding of the coke. The sintering ability of the coke after grinding was considered to result from the increase of surface energy, lattice distortion energy and fraction of volatile matters of the coke, which were induced by grinding treatment. (C) 1997 Elsevier Science Ltd

关键词: needle coke;semicoke;baking;mechanical properties;particle size;graphite

MICROSTRUCTURE AND PROPERTIES OF SiC_w/6061Al COMPOSITE The Author is now with Institute of Metal Research,Academia Sinica,China

MA Zongyi YAO Zhongkai Harbin Institute of Technology , Harbin , China

金属学报(英文版)

The SiC_w/Al composite prepared by squeeze casting has a combination of superior room temperature specific strength and modulus together with excellent thermal properties.The extrusion can make an improvement on the strength and ductility of the composite from 582 MPa as squeeze casted up to 639 MPa,and on the transformation from isotropic to the anisotropic structure.This seems to be explained by the orientation of whiskers and the densification of dislocations in matrix.TEM observation indicates that the stacking fault is the usual planar defect on the SiC_w surface. composite;;SiC whisker;;Al alloy;;microstructure

关键词: composite , null , null , null

Introduction to atmospheric corrosion research in China

Science and Technology of Advanced Materials

In this paper, we introduce the research on atmospheric corrosion in China. We describe the climate characteristics and the classification of atmospheric corrosivity across the whole country. We also describe the rusting evolution under simulated wet/dry cyclic conditions. (C) 2007 NIMS and Elsevier Ltd. All rights reserved.

关键词: atmospheric corrosion;corrosivity;rusting evolution;weathering steels;rust;mechanism;so2;o-3;no2

Development of Cast Superalloys for Gas Turbines in China

CHEN Rongzhang CHEN Wanhua Institute of Aeronautic Materials , Beijing 100095 , China.

材料科学技术(英文)

As in other countries,significant achievements in the research of cast superalloys for many years have also been obtained in China.These results are important contribu- tion to the development of aero and land-based gas tur- bine engines.

关键词: cast superalloy , null

R&D STATUS ON INTERMETALLICS IN CHINA

CHEN Guoliang(State Key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing Beijing 100083 , China)SHI Changxu (Academia Sinica , Beijing 100864 , China)

金属学报(英文版)

This paper briefiy introduces the R&D of intermetallics in China. R&D on intermetallics in a national scale in China began near ten years ago. The investigation in past years focused on the fundamental research and materials development. A significant progress has been made. Various components that made of Ti3Al Ni3Al, TiAl and Fe3Al have been successfully manufactured Some of them have been evaluted. It is expected that some intermetallic alloys will be produced in an industrial scale in the near future.

关键词: :intermetallic alloys , null , null , null

Further development of NdFeB magnet industry in China

Yang LUO

材料科学技术(英文)

Due to continued growth in key markets, a broadening of application base and performance improvements, the market demands of NdFeB magnet increased steadily in 1998, and the global output of sintered NdFeB magnet exceeded 10,000 t, in spite of the economic recession in Asia. In 1998 China produced 3,850 t sintered NdFeB block magnet, with an annual growth rate of +22% over the output in 1997.

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