材料期刊网

TEM STUDY OF MECHANISM OF STRAIN-AGE HARDENING OF INITIALLY DISORDERED (Co,Fe)_3V ALLOY

LIN Yijian Shanghai Iron and Steel Research Institute , ChinaS.GIALANELLA University of Trento , ItalyR.W.CAHN University of Cambridge , U.K. engineer , Shanghai Iron and Steel Research Institute , Shanghai 200940 , China

金属学报(英文版)

TEM study was made to explore the mechanism of the strain-age hardening of initially-dis- ordered (Co_(78)Fe_(22))_3V,which was found to be attributed to the formation of a special disloca- tion-stacking fault configuration in company with disorder-order transformation-disloca- tions extended to stacking faults on{111}planes and got connected with each other through partial dislocation reaction at intersections of{111}planes,leading to dense networks with cells bounded by stacking fault tetrahedrons.The results also indicated that ordered (Co_(78)Fe_(22))_3V has very low stacking fault energy on{111}planes and relative high and isotropie antiphase boundary energy,which implies that it is most likely to be Lomer-Cottrell locks,not Kear-Wilsdof locks,that are responsible for the high strength at high temperatures of this alloy.

关键词: (Co , 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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METASTABLE CHARACTERISTICS OF β-W

HUANG Huimin CHEN Xinmin Central South University of Technology , Changsha , China HUANG Huimin Associate Professor , Department of Chemistry , Central South University of Technology , Changsha , China

金属学报(英文版)

The nature of the oxygen contained in β-W was investigated with DSC,X-ray analysis on quenched samples and Auger spectroscope.It was shown that the oxygen contained in nonpyrophoric β-W consists of the reversibly chemisorbed oxygen and the interstitial oxygen which could form an interstitial solid solution with β-W.It seems better to consider β-W to be a metastable phase of tungsten with the interstitial oxygen as stabilizer.

关键词: tungsten , null , null , null

Effect of W on structural stability of TiAl intermetallics and the site preference of W

Physical Review B

The effect of W on the structural stability of TiAl intermetallic systems and the site preference of W in B2 and L1(0) TiAl were studied based on first-principles calculations. It was found find that about 15 at. % W addition, in good agreement with experiment, is required to stabilize the B2 structure in a TiAl base alloy. W was predicted to occupy Al sites in the B2 phase, but Ti sites in the L1(0) phase. The B2-stabilizing effect of W and its site preference can be explained perfectly on the basis of the pseudogap effect and the strong covalent W-Ti bonding. The strong W-Ti bonding pairs are maximized when W occupies Al sites in B2 TiAl. But when W occupies Al sites in L1(0) TiAl, the W-Ti bonding is weakened by the existence of Al in the alternating (002) plane, which can, however, strengthen the in-plane W-Ti bonding when W occupies Ti sites.

关键词: gamma-titanium aluminides;electronic-structure;microstructure;deformation;systems;alloys

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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Institute of Materials Science at Jilin University——A Brief Overview

WANG Yuming Institute of Materials Science , Jilin University , Changchun , 130023 , China

材料科学技术（英文）

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降低IF钢w(O)的工艺研究

王雄

钢铁研究 doi:10.3969/j.issn.1001-1447.2006.05.016

IF钢中w(O)的大小直接影响到成品板的表面质量.分析了武钢近年来IF钢w(O)偏大的生产现状,找到钢中w(O)、精炼处理前温度及钢包内炉渣等转炉冶炼、精炼及连铸工序对IF钢w(O)的影响,通过采用低氧钢生产工艺,使IF钢w(O)得到很好的控制.

关键词: IF钢 , w(O) , 转炉复吹

Valence bond structure of Ta-W alloys

Xiaobo LI , Youqing XIE

金属学报(英文版) doi:10.1016/S1006-7191(08)60099-X

The valence bond structure of substitutional BCC based Ta-W alloys is studied using characteristic crystal (CC) theory. This theory is based on cluster statistics of random alloys. By studying the correlativity between energy and volume of the CC in Ta-W alloys, the valence bond structure of CC is determined by the energy and shape method. Then, following additive law of CC, the valence bond structure of Ta-W alloys is calculated. It is found that the outer shell valence electronic distribution of Ta-W alloys shows a continuous change in the whole composition range. The covalent electrons e_c(d_c, s_c, and p_c) increase, whereas near free electrons e_f decrease with increasing W concentration. The bond length and single-bond radius decrease, whereas bond energy and bond valence increase with increasing W concentration. The mechanism of solid solution strengthening of Ta-W alloys is analyzed based on their valence bond structure.

关键词: Valence bond structure , null

Phase stability of Ta-W alloys

Xiaobo LI

金属学报(英文版)

The characteristic crystal model is applied to the study of phase stability and thermodynamics in substitutional bcc-based Ta-W alloys. The basic principle and method of alloy thermodynamics which is described by the characteristic crystal model is introduced in detail. The Gibbs energy of various phases including both disordered and ordered phases of the Ta-W system are evaluated. The phase diagram of Ta-W alloys is assessed and predicted. The results are in good agreement with experiments and better than that of first principle.

关键词: Ta-W alloys , phase diagram , characteristic crystal model , thermodynamics , phase stability

Microstructure characterization of long W core SiC fiber

材料科学技术（英文）

Microstructure of SiC fiber manufactured by chemical vapor deposition (CVD) onto tungsten (W) wire core was investigated by analytical electron microscopy (AEM). The results reveal that the fiber consists of W core, SiC sheath and C-coating. SiC sheath could be subdivided into two parts according to whether containing C rich stripe, or not. An emphasis was put on W/SiC interfacial reaction products and the transition zone between sub-layers in SiC sheath. The W/SiC interface consists of three layers of reaction production, namely, W2C, W5Si3 and WC. And there are amounts of facet faults existing in (100) face of WC crystalline and two classes of stack faults in WC have been revealed. The formation essence of different sublayers in SiC sheath was also discussed.

关键词: siC fiber;chemical vapor deposition (CVD);analytical electron;microscopy (AEM);C-rich zone;reaction products;chemical vapor-deposition;silicon-carbide;model;dichlorodimethylsilane;interface;pyrolysis;hydrogen;strength