关键词： 纳米复合材料   显微结构   非晶合金  

摘要： Ｔｉ８０－ｘＮｄｘＳｉ２０纳米复合材料的显微结构特征李斗星平德海叶恒强（中国科学院金属研究所固体原子像开放研究实验室，沈阳１１００１５）化学成分为Ｔｉ８０－ｘＮｄｘＳｉ２０（ｘ＝０，０．０５，０．１，０．２，０．４，０．８）合金，用锤砧快冷法制成Ｔｉ...

关键词： 超导体   亚稳微结构   超导电性  

摘要： 新材料ＲｕＳｒ２Ｇｄ１．４Ｃｅ０．６Ｃｕ２Ｏｚ中的亚稳微结构杨丽周贵恩唐凯斌＊张裕恒（中国科学技术大学结构分析开放研究实验室，＊中国科学技术大学应用化学系，合肥２３００２６）从平均结构上看，超导体Ｓｒ２ＲｕＯ４与高温铜氧化合物超导体类似，均为层状钙钛...

关键词： 氧化铝陶瓷   增韧   机械性能   显微结构  

摘要： 本文叙述了ＺｒＯ２增强增韧Ａｌ２Ｏ材料的制备，其中ＺｒＯ２有未被稳定的中入不同量稳定剂Ａｌ２Ｏ３或ＣｅＯ２于ＺｒＯ２中使其以亚稳四方和形式存在于基体ＡｌＯ２中，并测定其机械性能（硬度、抗弯强度、韧性），研究其不同的显微结构对性能的影响，以及探讨了ＺｒＯ２相变和微裂纹增韧机理。

关键词： Superalloys  

摘要： The microstructural features of MA 956 friction welds were examined using a combination of optical microscopy and transmission electron microscopy (TEM). The MA 956 base material contained a uniform distribution of small diameter (<20 nm) Y2O3 particles. Limited numbers of larger diameter (> 100 nm), spherically shaped Al2O3, Ti(C,N), Y2O3-Al2O3, and Al-Ti-Y containing particles were also observed in the MA 956 base material. In the recrystallized region, the grain size was largest at the bondline and increased markedly in the radial direction of the welded joint. Increasing the forging pressure from 50 to 150 MPa during the friction welding operation markedly increased the strain rate and decreased the grain size at the joint centerline. The friction welding operation substantially altered the particle chemistry, dimensions, and shape in the joint region. The number of aluminum-rich or titanium-rich particles was substantially decreased and large irregularly shaped particles were formed.

关键词： dislocations   grain boundaries   microstructures   crystal plasticity   finite strain  

摘要： Micro structurally-induced failure mechanisms in crystalline materials with coincident site-lattice (CSL) high angle grain boundaries (GBs) have been investigated. A multiple-slip rate-dependent crystalline constitutive formulation that is coupled to the evolution of mobile and immobile dislocation densities and specialized computational schemes have been developed to obtain a detailed understanding of the interrelated physical mechanisms that result in material failure. A transmission scalar has also been introduced to investigate slip-rate transmission, blockage and incompatibility at the GB. The combined effects of high angle GB misorientation, mobile and immobile dislocation densities, strain hardening, geometrical softening, localized plastic strains, and slip-rate transmission and blockage on failure evolution in face centered cubic (f.c.c.) crystalline materials have been studied. Results from the present study are consistent with experimental observations that single dislocation pile-ups result in a transgranular failure mode for the Sigma 9 CSL GB, and that symmetric double dislocation pile-ups result in an intergranular failure mode for the Sigma 17b CSL GB. Copyright (C) 1996 Elsevier Science Ltd

关键词： 尖晶石   显微结构   耐火材料  

摘要： 在方镁石－尖晶石－ＺｒＯ２－硅酸盐相结构中，发现由于ＺｒＯ２的存在，可提高主晶相方镁石与尖晶石的结构完整性。同时ＺｒＯ２又吸收并富集了大量的ＣａＯ成分，形成ＣａＺｒＯ３布于晶间，阻断硅酸盐相的扩散路径，封闭气孔．并有形成原位生长的含有ＣａＯ·ＺｒＯ２高粘弹基质相的趋势，在遇渣侵蚀时这种现象更为明显。

关键词： 非连续增强金属基   复合材料   界面微结构   分析透射电镜   示差扫描量热计  

关键词： 界面演化   有限元   蒸发-沉积机制   表面扩散   能动量张量  

关键词： 微电子机械系统   航天器  

摘要： 航天器微型化的新突破──微电子机械系统朱毅麟近年来，由于微电子技术的迅速发展，航天器使用的电子部件和系统早已告别了分立元器件的时代，用上了集成电路，甚至大规模集成电路。空间电子系统不仅实现了小型化、微型化，而且正在向着商业化迈进。有了这样的基础，国外...

关键词： Thin films   Nonlinear optics   Layers   Chromophores   Deposition  

摘要： This paper describes the synthesis and characterization of self-assembled second-order nonlinear optical multilayer materials containing the high-hyperpolarizability [(aminophenyl)azo]pyridinium chromophore. The chromophoric multilayers are assembled on clean glass or single-crystal silicon substrates via the following iterative reaction sequence: (1) treatment with 4-ClCH2C6H4SiCl3, 3-BrC3H6SiCl3, or 3-IC3H6SiCl3 to afford a self-assembled coupling layer;(2) quaternization of 4-[[4-[N,N-bis(hydroxylethyl)amino]phenyl]azo]pyridine in a ''topotactic'' fashion to generate an [(aminophenyl)azo]pyridinium chromophore layer;(3) cross-linking with octachlorotrisiloxane to afford a capping layer (which also regenerates surface hydroxyl groups for subsequent layer deposition). The new chromophore precursor 4-[[4-[N,N-bis(hydroxylethyl)-amino]phenyl]azo]pyridine was synthesized by diazotization of LC-aminopyridine followed by coupling with N-phenyldiethanolamine and has been characterized by elemental analysis, mass spectrometry, and infrared, UV-vis, and NMR spectroscopies. The chromophoric multilayers have been characterized by X-ray photoelectron and transmission optical spectroscopies, spectroscopic ellipsometry, X-ray reflectivity, advancing contact angle measurements, and polarized second harmonic generation (SHG). The excellent structural regularity of the chromophoric multilayers is indicated by the linear dependence of the [(aminophenyl)azo]pyridinium chromophore longitudinal HOMO --> LUMO charge-transfer excitation absorbance at 572 nm and the ellipsometry- and X-ray reflectivity-derived multilayer thicknesses on the number of assembled trilayers, while the uniform polar order of the stacked chromophoric multilayers is evidenced by the quadratic dependence of the second harmonic generation intensities on the number of trilayers. The [(aminophenyl)azo]pyridinium multilayers are photochemically stable, have very high structural regularities, and exhibit a second-orde