材料期刊网

Microstructures and Mechanical Properties of Al/Mg Alloy Multilayered Composites Produced by Accumulative Roll Bonding

H.S. Liu B. Zhang G.P. Zhang

材料科学技术（英文）

Al/Mg alloy multilayered composites were produced successfully at the lower temperature (280°C) by accumulative roll bonding (ARB) processing technique. The microstructures of Al and Mg alloy layers were characterized by scanning electron microscopy and transmission electron microscopy. Vickers hardness and three-point bending tests were conducted to investigate mechanical properties of the composites. It is found that Vickers hardness, bending strength and stiffness modulus of the Al/Mg alloy multilayered composite increase with increasing the ARB pass. Delamination and crack propagation along the interface are the two main failure modes of the multilayered composite subjected to bending load. Strengthening and fracture mechanisms of the composite are analyzed.

关键词: Accumulative roll bonding (ARB) , Al/Mg alloy multilayered composite , Ultra-fine grains , Hardness , Bending properties

Microstructures and Mechanical Properties of Al/Mg Alloy Multilayered Composites Produced by Accumulative Roll Bonding

H.S. Liu B. Zhang G.P. Zhang

材料科学技术（英文）

Al/Mg alloy multilayered composites were produced successfully at the lower temperature (280°C) by accumulative roll bonding (ARB) processing technique. The microstructures of Al and Mg alloy layers were characterized by scanning electron microscopy and transmission electron microscopy. Vickers hardness and three-point bending tests were conducted to investigate mechanical properties of the composites. It is found that Vickers hardness, bending strength and stiffness modulus of the Al/Mg alloy multilayered composite increase with increasing the ARB pass. Delamination and crack propagation along the interface are the two main failure modes of the multilayered composite subjected to bending load. Strengthening and fracture mechanisms of the composite are analyzed.

关键词: Accumulative roll bonding (ARB) , Al/Mg alloy multilayered composite , Ultra-fine grains , Hardness , Bending properties

Mg-Zn系合金G.P.区和时效强化的研究进展

陈敬区 , 刘江文

材料导报

评述了国内外Mg-Zn系合金的研究进展.总结了Mg-Zn系合金中时效析出行为和各析出强化相的特征,通过分析铝合金G.P.区的形成规律,探讨了Mg-Zn系合金G.P.区的存在可能性.指出Mg-Zn系合金G.P.区的研究对Mg-Zn合金析出相变理论和发展高强度铗合金具有重要意义.

关键词: Mg-Zn系合金 , G.P.区 , 时效 , 析出强化

Jian ZHANG/Langhong Lou

材料科学技术（英文）

关键词:

Relationship between the brittlement susceptibility and H permeation current for UNS g11180 steel in 5% NaCl solution with H2S

材料科学技术（英文）

Sulfide stress corrosion cracking (SSCC) behaviour of UNS G11180 steel in 5% NaCl solution with H2S was, studied by slow strain rate tensile test (SSRT), SEM and electrochemical hydrogen permeation technique. The results reveal different cracking mechanism and H permeation current (I-H) through UNS G11180 steel plate in different concentration of H2S solution. The susceptibility to SSCC of UNS G11180 steel in 5% NaCl solution with H2S was evaluated by the permeation current (I-H, mu A), which depends on the concentration (c x 10(-6)) of H2S by the equation: I-H = 8.525 x c(0.7249). It is proved that the electrochemical H permeation method is a practical way to assess the susceptibility to SSCC.

关键词: cracking

Role of P, S and B on creep behavior of alloy 718

材料科学技术（英文）

The doping of phosphorus, sulfur and boron in IN718 superalloy can remarkably influence the creep behavior. The modifications of the minor elements seem not to vary the stress exponent and the influences primarily concentrate on the effective diffusion coefficient. A pronounced beneficial interaction between P and B and a weaker detrimental interaction between P and S have been obtained. The preexponential frequency constant is proved to be strongly related with the creep activation energy because of the so-called compensation effect. The compensation temperature has been determined to be about 1080 K, which corresponds to the transformation temperature from rapidly coarsened gamma " phase to delta phase. It has been proposed that trace elements can influence the effective diffusion coefficient individually or cooperatively, which in turn either retard or speed the creep process.

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Relationship between the Brittlement Susceptibility and H Permeation Current for UNS G11180 Steel in 5% NaCl Solution with H_2S

Xueyuan ZHANG and Yuanlong DU(State Key Lab. for Corrosion and Protection , Institute of Corrosion and Protection of Metals , Chinese Academy of Sciences , Shenyang 110015 , China)

材料科学技术（英文）

Sulfide stress corrosion cracking (SSCC) behaviour of UNS G11180 steel in 5% NaCl solution with H2S was studied by slow strain rate tensile test (SSRT), SEM and electrochemical hydro gen permeation technique. The results reveal different cracking mechanism and H permeation current (IH) through UNS G11180 steel plate in different concentration of H2S solution. The susceptibility to SSCC of UNS G11180 Steel in 5% NaCl solution with H2S was evaluated by the permeation current(IH, μA), which depends on the concentration (c×10-6) of H2S by the equation:IH = 8.525 ×c0.7249. lt is proved that the electrochemical H permeation method is a practical way to assess the susceptibility to SSCC.

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Explanation of the EPR g factors for Co2+ impurities in trigonal Cd2P2S6 crystal

Physica B-Condensed Matter

By extending the theory of Abragam and Pryce, the formulas of EPR parameters g and g(perpendicular to) for 3d(7) ion in trigonal octahedral crystals are established from a cluster approach. In these formulas, not only the configuration interaction effect, but also the covalency effect are considered and the parameters related to both effects and the trigonal distortion are determined from the optical spectra and the structural data of the crystal under study. Based on these formulas, the g(parallel to) and g(perpendicular to) of Cd2P2S6: Co2+ crystal are reasonably explained from its structural data. The relationship between the sign of Deltag (= g(parallel to) - g(perpendicular to)) and the trigonal distortion (elongated or compressed) of ligand octahedron, which is opposite to that obtained in the previous paper, is given and the results are discussed. (C) 2001 Elsevier Science B.V. All rights reserved.

关键词: electron paramagnetic resonance;crystal- and ligand-field theory;trigonal distortion;Co2+;Cd2P2S6;superposition model;transition;complexes;ion

Studies of the g factors and zero-field splitting for the trigonal Ti-Ga(2+)-S-p defect center in GaP crystal

Spectrochimica Acta Part a-Molecular and Biomolecular Spectroscopy

The EPR g factors g(parallel to), g(perpendicular to) and zero-field splitting D suggested to be caused by a donor-acceptor nearest-neighbour pair defect [Ti-Ga(2+)-Sp] in GaP:Ti2+ co-doped with sulphur are calculated from the high-order perturbation formulas based on a two spin-orbit coupling parameter model for the EPR parameters of 3d(2) ion in trigonal symmetry. The calculated results are close to the observed values. The suggestion of [TiGa2+-Sp] pair defect in GaP:Ti co-doped with sulphur is also confirmed from this calculation. (C) 2002 Elsevier Science B.V. All rights reserved.

关键词: electron paramagnetic resonance;crystal- and ligand-field theory;pair;defect;Ti2+;GaP;superposition model;identification;transition;impurities;epr;co

高含H₂S/CO₂环境中P110钢应力腐蚀

崔世华 , 李春福 , 王朋飞 , 邓洪达

中国腐蚀与防护学报

用恒载荷拉伸法，结合腐蚀电化学测试技术和断口扫描电镜（SEM）分析技术，研究了P110钢在H₂S/CO₂NACE标准溶液中的硫化物应力腐蚀 (SSCC)行为。结果表明，随着溶液中的H₂S含量增高，P110钢的自腐蚀电位（E _corr}）急剧下降，至极小值后缓慢升高，约5 h后达到稳定值直至断裂，试样呈解理状脆性断口；随溶液中通入CO₂量的增大，P110 钢的自腐蚀电位（E_corr）稍有增高，自腐蚀电流（I_corr}）减小，试样断裂时间延长，断口由脆性解理向韧窝状韧性转化。这种现象的产生与H₂S/CO₂在钢表面的竞争吸附及P110钢在应力腐蚀环境中表面膜的拉伸破裂与再生有关。

关键词: P110 , H₂S/CO₂ , sulfide stress corrosion cracking