Three types of tungsten electrodes containing three rare earth oxides, namely Y2O3, La2O3, and CeO2 and one with Y2O3 and CeO2 were prepared, in which the total contents of rare earth oxides are 2.2% in mass, and the characteristics of these electrode materials were studied. By TIGwelding, the welding characteristics including arc starting, arc static properties and electrode consumption of these electrodes were also analyzed. The results suggest that the electrodes added three rare earth oxides are more favorable for pro2 cessing than that added two rare earth oxides. All the electrodes activated with two or more rare earth oxides are more superior to W2ThO2 in operating, and the electrode combined with Y2O3 and CeO2 shows the best properties when it is used at a heavy current for a long time. The analyses of the results of electrode consump2 tion indicates that the rim forming during arcing is one of the important reasons for electrode's heavy erosion, and the increased Y2O3 content in electrodes is beneficial to retard the formation of rim, and leads to the im2 provement of consumption resistance of the electrodes.

A brief review of the recent advances in the field of ecomaterials in China is presented, giving opinions on the current activities and suggesting possible future courses of action. The past 10 years has seen the development of the concept of ecomaterials involving practical research and development of environmentally conscious materials, and the establishment of related systems including national programs and laws. It has been an important period for the development of materials science and the goal of creating a sustainable society in China. It has now become clear that ecomaterials, which exhibit high performance whilst being environmentally benign in their life cycle, are evolving from being only materials for end-of-pipe applications to include all materials being designed on the basis of life-cycle thinking.

The synthesis ofCe-Wcomposite nanopowder plays an important role in the preparation of relevant alloys. In the paper, theCe-Wcomposite nanopowder were prepared by liquid-liquid mixing, freeze drying, and two-stage reduction. The particle size of the powder produced is in the range of 20 and 30 nm. Homogeneous microstructure and uniform distribution of Ce were found in this powder. The phase compositions during the producing process of nanopowder were studied by XRD. The appearances of the freeze-dried powder, the first-reduced treated powder, and the finally obtained nanopowder were analyzed by SEM, FESEM, as well as TEM. Research results showed that most of the powders existed in the non-hygroscopic and non-crystalline state. The final product of the experiments was the W-Ce2WO6 nanopowder, which existed in the form of crystalline state. IR analysis indicated that the freeze-dried powder remained a Keggin structure. In addition, the TG and DTA thermal analysis explained that the losing water contained in the powders could be processed in three stages.

In this paper La-Sc-Mo cathode has been prepared and its electron emission ability was measured. This type of cathode shows good electron emission performance that the saturated current density is 6.74 A cm 1 and the work function is about 2.59 eVat 1300 ℃, which is much lower than thoriated tungsten cathode (Th-W). So it is a potential cathode to replace the Th-W cathode with radioactive pollution. Surface analysis shows that good emission ability due to the 20 nm surplus La layer and the element Sc may do good to the La diffusion to the surface.

The microstructures and textures in the cold rolled aluminium strip at different strains have been investigated. The rolling reductions of interest were from 25 %(ε=0.28) to 92.5%(ε=2.59). The mechanical properties of the strip at different angles to rolling direction were measured by uniaxial tensile test2 ing. The pole figures were determined with D2500 X2ray diffraction goniometer and ODF's were calculated by Bunge's method. The microstructures were studied by TEM. It was shown that the textures developed in the strip were different from those developed in the plate. The development of the microstructures, textures and mechanical anisotropy in the strip was analyzed. The influence of microstructures and textures on the plastic anisotropy was discussed.

The changes of the valence state of lanthanum in the Mo-La2O3 model cathode specimens were systemati-cally studied by in-situ XPS/ AES analyses from room temperature to 1550 ℃. The experimental results show that the valence of lanthanum changes during the activation processes. As the temperature increases, the lattice oxygen in La2O3 is dissociated, resulting in partial reduction of the lanthanum to LaOx (x<3/2). In addition, the lan-thanum-rich phase diffuses from bulk into the surface of the sample. The lack of lattice oxygen in this phase has a favorable effect on emission, which leads to a lower work function for the Mo2La2O3 cathode.

Lanthanum2containing cathodes are an attractive alternative to thorium tungsten cathodes be2 cause of their low work function and their comparatively low operating temperatures. A La2Mo carbonized cathode was described, which had a high thermionic emission; it was made up in a similar way to the Th2W cathode, but possesses high emission values. The thermionic tube equipped with La2Mo carbonized cathode was designed for comparison with Th2W cathode tube. It was experimentally verified that La2Mo cathode has higher thermionic emission effectiveness and its operating temperature is about 200 ℃lower than that of Th2W cathode. The emission current density of La2Mo wire satisfies for electron tubes as Th2Wfilament. A stable e2 mission current has been obtained with La2Mo carbonized cathode tubes for more than 1 800 h. From the re2 sults it is clear that the emission stability of La2Mo cathode satisfies the requirements for the replacement of Th2W filament.

利用电子显微分析（TEM）和oDF织构分析，研究了纵横轧制铝板再结晶退火前后的织构和再结晶过程。直接观察到再结晶过程中的选择长大，经电子衍射分析了新晶粒的取向，并通过极图分析了各织构组分<111>间的关系。结果表明，纵横轧制铝板再结晶过程中存在选择生长现象，并最终决定再结晶织构；面心立方金属中这种取向关系约为40°<111>。

本文研究了稀土氧化物在钨极氩弧焊（TIG焊接）用复合稀土钨电极材料中的作用及行为采用sEM方法观察燃弧旨电极尖部的表面形貌，并通过EDAX能谱分析对稀土元素在电极尖部表面上的分布进行探测，用光学显微分析（OM）方法观察燃弧后电极尖部轴向剖面的金相组织，采用AES深度剖析方法考察燃弧前后稀土元素在电极尖部表层的分布特征结果表明，不同稀土氧化物在电极工作时的行为不同。复合稀土钨电极中稀土氧化物的协同作用有利于电极综合性能的提高

通过粉末冶金和压力加工制备了系列二元复合稀土钨电极材料（w-La203-Y203，w-La203-ce02，w-Y203-ce02），采用直流正接（DcsP）的钨极氩弧焊（TIG）方法，系统研究了它们的焊接电弧特性，包括引弧性能、电弧静特性和电极抗烧损性能，并对它们的这些性能与单元稀土钨电极材料（w-La203，w-ce02，w-Y203）和钍钨电极材料进行了比较。结果表明二元复合稀土钨电极性能优于单元稀土钨电极和钍钨电极。