材料期刊网

ELECTROCHEMICAL BEHAVIOUR OF PHASES IN TITANIUM ALLOYS

LIU Ping Institute of Aeronautical Material , Beijing , ChinaXU Changgan Beijing University of Aeronautics and Astronautics , Beijing , China XU Changgan , Associate Professor , Group 102 , Beijing University of Aeronautics and Astronautics , 37 Xueyuan Road , Beijing 100083 , China

金属学报(英文版)

The electrochemical behaviour,which is presented by means of anodic polarization curves.of the component phases in Ti and Ti alloys in aqueous solutions of fluorhydrie acid,chhnhydric acid and amber acid has been investigated.The results indicate that the electrochemical behaviour of the allloys depends upon the composition and the lattice type.The corrosion of x and x′phase in actire region and that of β phase in passive region are the dominant corrosion behaviour.

关键词: Ti alloy , null , null

EFFECIS OF TEMPERATURE AND OVERLOAD RETARDATION ON CORROSION FATIGUE CRACK GROWTH OF HIGH STRENGTH STEEL

QIAN Yourong HE Xiangdong Beijing University of Aeronautics and Astronautics , Beijing , China QIAN Yourong , Dept.of Materials Science and Engineering , Beijing University of Aeronautics and Astronautics , Beijing 100083 , China

金属学报(英文版)

The fatigue crack growth rate (CGR) of ultra high strength steel 30CrMnSiNi2A in distilled water at 18,35 and 55℃ were measured.It was confirmed that the temperature is strongly af- fected on the corrosion fatigue CGR of ultra high strength steel.An expression concerning the effects of Δ K and temperature on the CGR was proposed.The fact that the apparent activation energy (36.6 kJ/mol) resulted from regressive analysis of CGR data was similar to the activation energy of hydrogen diffusion in γ-Fe,strongly supporting the theory of hydrogen-assisted crack growth.The overload retardation effect was greatly reduced in cor- rosion fatigue crack growth,especially at lower frequency,e.g.,0.1 Hz.This phenomenon might be due to the increase of the SCC component of CGR after an overload.

关键词: corrosion fatigue , null , null , null

STATISTICAL MODEL FOR FRACTURE TOUGHNESS OF A MODIFIED Al-7Si-0.45Mg CAST ALLOY

ZHANG Guobin CHEN Changqi Beijing University of Aeronautics and Astronautics , Beijing , China Dept.of Materials Science and Engineering , Beijing University of Aeronautics and Astronautics , Beijing 100083 , China

金属学报(英文版)

The statistical model for the fracture toughness of a modified Al-7Si-0.45Mg cast alloy has been proposed on the basis of analysis of the correlation between the size distribution of crack nuclei and Si particles and of the micromechanism of fracture.The suitable criterion of frac- ture toughness according to the model has been given.The model has found a good explana- tion for the fracture feature,fracture toughness and microstructure,and agreed with the ex- periments very well.

关键词: cast Al alloy , null , null

INVESTIGATIONS ON THE FORMATION OF INITIAL CRACKS IN THERMAL BARRIER COATINGS PREPARED BY EB-PVD

S.K.Gong , L. Deng , F.S.Liu and H.B.Xu(Department of Material Science and Engineering , Beijing University of Aeronautics and Astronautics , Beijing 100083 , China Manuscript received 26 August 1996)

金属学报(英文版)

This paper deals with the mechanism of the formation of initial cracks in the yttria partially stabilized zirconia thermal barrier coatings prepared by EB-PVD method.The microcracks were only recognized inside the ceramic top coat of the thermalcycled TBCs. SEM/EDS observations indicated that some special oxides exist in the area just below the cracks.It seems that the formation of the initial cracks can result from the oxidation stress as well as the thermal stress.

关键词: :TBCs , null , null , null

Effect of Sintering Temperature on Microwave Absorbing Behaviour of Mn-Zn Ferrite

Yongxue GAN Pei YI Changqi CHEN (C.Q.Chen) Dept.of Mater.Sci.Eng. , Beijing University of Aeronautics and Astronautics , Beijing 100083 , China

材料科学技术（英文）

The microwave absorbing behaviour of Mn-Zn ferrite sintered at 1100,1200,1300,1400 and 1500℃ has been investigated.The phase constitution of the ferrite was analyzed by X-ray diffraction.The results show that the ferrite sintered at 1 500℃ has better microwave absorbing prop- erty than those prepared at other temperatures,due to the increase of turbulent loss generated by the formation of excessive Fe~(2+) in deoxidizing of Fe_2O_3 at high temperatures.

关键词: Mn-Zn ferrite , null , null

EFFECTS OF RETAINED AUSTENITE ON DUPLEX MICROSTRUCTURE OF MARTENSITE AND LOWER BAINITE

WEN Cui'e , LIN Jianguo , ZHOU Yajian(Department of Materials Science , Beijing University of Aeronautics and Astronautics , Beijing 100083 , China) Manuscript received 9 May 1995

金属学报(英文版)

The morphology and amount of the retained austenite in the duplex microstructure of martensite and tower bainite of a tow,alloy cold die steel(it is called GD steel for short) with high strength and high toughness have been investigated.The thermal and mechanical stabilities of the retained austenite were analyzed.Furthermore the effects of retained austenite on the mechanical properties of the steel were studied.The results show that the morphology and amount of retained austenite vary with silicon content in the steel.Retained austenite with high stability was responsible for the simultaneous increase in strength and toughness of the steel.The duplex microstructure of martensite and abnormal lower bainite of the steel with the maximum silicon content exhibits a relatively good strength-toughness combination.

关键词: :martensite , null , null , null

University of Science and Technology Beijing

JIA Shizhen University of Science and Technology Beijing , China.

材料科学技术（英文）

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Abstracts of papers from Journal of University of Science and Technology Beijing

稀有金属（英文版）

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CORRELATION BETWEEN STRESS COMPONENTS AND STRESS CORROSION CRACKS IN BRASS Lecturer,Department of Materials Physics,University of Science and Technology Beijing,Beijing 100083,China

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 , 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）

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