材料期刊网

Ti Based Metal Matrix Composites Produced by Powder Metallurgy Routes

Z.G.Liu , B.Gabbitas , D.L.Zhang , J.Liang , W.Gao

材料科学技术（英文）

The production and microstructural characterization of two types of ceramic particulate reinforced Ti matrix composites (TMCs): Ti-6Al-4V/10~vol. pct TiB and Ti(Al,O)/58 vol. pct Al2O3 were studied. The Ti-6Al-4V/10 vol. pct TiB composite with refined microstructure has been produced using a combination of high energy mechanical milling and hot isostatic pressing. The Ti(Al,O)/58 vol. pct Al2O3 in-situ composite powder has been produced using a novel powder processing process which involves high energy mechanical milling of a mixture of Al and TiO2 powders to produce an Al/TiO2 composite powder followed by thermal treatment of the composite powder. The Ti(Al,O)/58 vol. pct Al2O3 composite powder has been used to produce coatings. Selected mechanical properties of the Ti-6Al-4V/10 vol. pct TiB composite and the high temperature oxidation resistance have also been evaluated.

关键词: Ti alloy , null , null , null

Crystal structure and photoluminescence of Tb3+ doped Y3GaO6

Journal of Alloys and Compounds

A solid solution with formula (Y1-xTbx)(3)GaO6 (x = 0-0.5) was prepared by solid-state reaction method. Powder X-ray diffraction (XRD) shows that Y3GaO6 is isostructural to Gd3GaO6 (Cmc2(1)), and the lattice parameters are a = 8.8364(1) angstrom, b = 11.0899(1) angstrom and c = 5.3937(1) angstrom. Atomic parameters were derived by Rietveld refinement of the XRD pattern. Photoluminescence (PL) spectra show a strong green emission of 543 nm from the D-5(4) -> F-7(5) transition of Th3+ at room and liquid nitrogen temperature. There is a wide saturation range of the PL intensity for the Th3+ content from x = 0.04-0.20, and a long life time about 1200 mu s for the green 543 nm emission at room temperature. (c) 2006 Elsevier B.V. All rights reserved.

关键词: Y3GaO6;crystal structure;Tb3+ doped;photoluminescence;luminescence properties;dependence;y3al5o12;phosphor;ions;ce3+;tb-3;uv

A systematic study on crystal structure and magnetic properties of Ln(3)GaO(6) (Ln = Nd, Sm, Eu, Gd, Tb, Dy, Ho and Er)

Journal of Solid State Chemistry

The crystal structures of a series of compounds with the composition Ln(3)GaO(6)(Ln = Nd, Sm, Eu, Gd, Tb, Dy, Ho and Er) synthesized by solid-state reaction at 1400degreesC are investigated. X-ray diffraction shows that Ln3GaO6 has a non-centro symmetric orthorhombic structure (space group Cmc2(1)). Lattice parameters a, b, c and cell volume and the average distances between Ln(l)-O, Ln(2)-O of these compounds decrease with the decreasing of the radii of trivalent Ln ions, which accord with the expected lanthanide contraction behavior. There are two sites of seven-fold coordination for Ln atoms with oxygens, and Ga atoms are in oxygen tetrahedra which are distorted and elongated along the a-axis. Magnetization measurements indicate that the susceptibility X changes with temperature in Curie-type manner. (C) 2004 Elsevier Inc. All rights reserved.

关键词: Ln(3)GaO(6);crystal structure;Rietveld refinement;X-ray diffraction;garnets

Optical spectra of Ln(3+)(Nd3+, Sm3+, Dy3+, Ho3+, Er3+)-doped Y3GaO6

Journal of Luminescence

Ln(3+) (Ln = Nd, Sm, Eu, Gd, Dy, Ho, Er)-doped Y3GaO6 compounds were prepared by solid-state reaction, and their optical spectra such as absorption, photoluminescence, excitation and time-resolved spectra have been measured for Ln Nd, Sm, Dy, Ho, Er. X-ray powder diffraction shows that the lattice parameters of the compounds (Y(0.96)Ln(0.04))(3)GaO6 decrease with the decrease of the radii of trivalent Ln(3+) ions, indicating that Ln(3+) ions have substituted for y(3+) ions in the lattice. Optical spectra show that there are obvious absorptions at ultraviolet to visible region. The strong emissions in visible and infra-red region show that Y3GaO6 is a suitable host for rare-earth-doped laser crystal and phosphor materials. (C) 2004 Elsevier B.V. All rights reserved.

关键词: crystal-field;absorption-spectra;luminescence;y3ga5o12;glasses;garnet;y2o3;ions;laf3;tb3

Optical properties of (Y1-xTmx)(3)GaO6 and subsolidus phase relation of Y2O3-Ga2O3-Tm2O3

Journal of Solid State Chemistry

A serial of samples in Y2O3-Ga2O3-Tm2O3 pseudo-ternary system are prepared by solid-state chemical reaction method. The range of solid solution in (Y1-xTmx)(3)GaO6 is 0 < x < 0.384. Powder X-ray diffraction shows that the compounds crystallize in Gd3GaO6 (Cmc2(1))-type structure. The solid solubilities of Y3+xGa5-xO12 (x = 0-0.77) and Tm3+xGa5-xO12 (x = 0-0.62) are 37.5-47.11 at% Y2O3, and 37.5-45.26 at% Tm2O3, respectively. PL spectra of Tm-doped Y3GaO6 show that there is a sharp blue emission at similar to 456 nm from the D-1(2) -> F-3(4) transition at room temperatures with two lifetimes (similar to 5 and similar to 15 mu s) and a narrow saturation range of PL intensity for the Tm3+ content from x = 0.005 to 0.03. The sharp emission and long lifetime of (Y1-xTmx)(3)GaO6 indicate that Y3GaO6 is a potential phosphor and laser crystal host material. (c) 2005 Elsevier Inc. All rights reserved.

关键词: Tm3+ -doped Y3GaO6;Y2O3-Ga2O3-Tm2O3 system;(Y1-xTmx)(3)Ga5O12 solid;solution;luminescence;crystal-structure;luminescence;phosphor;cations;ions;tb3

不同温度下碳源对AOA-SBR工艺PAO与GAO竞争释磷的影响

张兰河 , 李德生 , 王旭明 , 张海丰

硅酸盐通报

为了提高生物除磷效率,研究采用AOA-SBR工艺进行了长期连续除磷实验,考察不同温度下碳源(乙酸钠、丙酸钠、葡萄糖)对PAO与GAO竞争的影响.结果表明:当温度由10℃升高至25℃时,利用丙酸钠作为碳源时,污泥含磷量与含糖量分别从7.2％和5.1％升高至7.9％和6.3％,PHA转化量升高了23.1 mg/L,厌氧释磷量从105.9 mg/L升高至149.9 mg/L,VSS/MLSS由71％降低至65％;利用乙酸钠作为碳源时,污泥含磷量与含糖量分别从6.9％和5.3％升高至7.6％和6.7％,PHA转化量升高了23.9 mg/L,厌氧释磷量从73.8 mg/L升高至108.8 mg/L,VSS/MLSS由73％降低至71％;利用葡萄糖作为碳源时,污泥含磷量与含糖量分别从5.8％和6.3％升高至6.6％和8.8％,PHA转化量升高了33.2 mg/L,厌氧释磷量从37.4 mg/L升高至43.2 mg/L,VSS/MLSS由80％升高至88％.当温度升高至30℃时,3个反应器均出现厌氧末期PHA浓度下降和糖原浓度升高,厌氧释磷量减少,污泥含磷量均下降,污泥含糖量上升,VSS/MLSS均很高.与葡萄糖相比,采用乙酸钠和丙酸钠作为碳源,有利于PAO生长繁殖,PAO为优势菌种,抑制GAO增殖.同时,低温更有利于PAO的生长繁殖.

关键词: 温度 , 碳源 , SBR , PAO与GAO

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

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