关键词： 微结构材料   半导体材料  

摘要： 超晶格的概念与先进的材料生长技术相结合产生了半导体微结构材料。目前，材料设计、材料生长和深微米技术的一体化，推动着半导体微结构材料向着低维化方向发展。

关键词： 掺杂   显微结构   陶瓷   压敏陶瓷   氧化锌   电性能  

摘要： 本文探讨了多种金属氧化物对ＺｎＯ－Ｂｉ＿２Ｏ＿３－ＴｉＯ＿２系材料的改性作用和对其微结构的影响，为得到预定性能的材料提供了掺杂方面的实验依据。

关键词： High temperature superconductors  

摘要： Self-field critical current density (J(c)) data on Ag-clad Bi1.7Pb0.4Sr1.8Ca2Cu3.5Ox tapes prepared using low-purity commercial-grade (98-99%) starting materials are presented. J(c) is found to be increasing with decreasing core thickness. Tapes with a 7 mu m thick core and prepared with repeated rolling and sintering have J(c) = 6.14 X 10(3) A cm(-2) at 77 K and 1.49 X 10(5) A cm(-2) at 4.2 K. TEM investigations on these tape specimens reveal a number of microstructural features which might be acting as nux-pinning sites and might thus be responsible for J(c) values higher than for corresponding tapes prepared with high-purity (99.99%) materials.

关键词： 钛酸锶铅基   陶瓷   烧成   热处理   PTCR  

摘要： 研究了烧成及热处理工艺对钛酸锶铅基热敏材料的阻温特性及显微结构的影响。通过扫描电镜（ＳＥＭ）和能量分散仪（ＥＤＡＸ）分析了材料的显微结构及不同形貌晶粒的成份。通过对组成、烧成及热处理工艺的控制，可得到具有Ｖ型ＰＴＣＲ特性的热敏材料。

关键词： 显微结构   耐火材料   含碳   配料  

摘要： 本文探讨了Ｓｉ及α－Ａｌ２Ｏ３超细粉对Ａｌ２Ｏ３－ＺｒＯ２－Ｃ系材料显微结构的影响．认为在Ａｌ２Ｏ３－ＺｒＯ２－Ｃ系材料中同时加入Ｓｉ和α－Ａｌ２Ｏ３超细粉，Ｓｉ粉除了与Ｃ生成了ＳｉＣ纤维外，其反应产物ＳｉＯ２还与α－Ａｌ２Ｏ３超细粉及ＺｒＯ２生成了莫来石（Ａ３Ｓ２）和Ａｌ２Ｏ３－ＺｒＯ２－ＳｉＯ２（ＡＺＳ）固溶体，这些新生成的矿物相对试样的显微结构产生重要的作用．

关键词： 碳纤维   铝合金   复合材料   微结构  

摘要： 本文研究用真空压力浸渍法制造的Ｃ／纯Ａｌ和Ｃ／Ａｌ－Ｃｕ两种复合材料界面微观结构的差异。探求合金化元素Ｃｕ的作用本质。结果表明，Ｃ／Ａｌ－Ｃｕ复合材料界面存在有ＣｕＡｌ＿２、Ａｌ＿４Ｃ＿３、ＡｌＣｕ三种脆性化合物，还发现ＣｕＡｌ＿２对Ａｌ＿４Ｃ＿３的形核影响不明显，但对它的长大有抑制作用。正是由于这种影响，使Ｃ／Ａｌ－Ｃｕ复合材料的耐用温度提高。

关键词： Fiber reinforced materials  

摘要： The ''multi-step'' braiding process is introduced as an extension to the four-step braiding process. This process greatly enlarges the possibilities of braid microstructures. An assumed yarn packing arrangement within the braided preform and geometric considerations were used to relate yarn orientation to non-dimensional pitch length. Further, study of the fundamental principles of track and column braiding yielded a relationship between track/column shifting sequence and yarn orientation, pitch length, and yarn diameter. Coupled via. computer software, these relationships provide a link between design parameters such as preform size, yarn diameter, and microstructure to operating parameters such as pitch length and shifting sequence. Additionally, the volume of yarn in a given pitch length divided by that pitch length has been predicted. This supplies a simple method of calculating fiber volume fraction. Experimentally measured yarn volume fraction and yarn orientation have shown close agreement with theoretical predictions.

摘要： The ageing, tensile and fatigue behaviour of a 2124 (Al-Cu-Mg) alloy reinforced with SiC particles have been studied. The MMC has been studied in the solution treated and pre-strained conditions and its behaviour has been compared directly to the unreinforced alloy. Ageing is accelerated in the MMC compared to the unreinforced alloy and this has been shown using differential scanning calorimetry (DSC) to be associated with enhanced S' formation. Arrhenius analysis shows that the activation enthalpy for diffusion is reduced in the MMC compared to the unreinforced alloy. DSC scans indicate that whilst GPB zone growth is much reduced in the solution treated MMC, nucleation is enhanced. This observation is in conflict with the commonly accepted "decreased vacancy" theory and a new model has been proposed to explain this observation. The tensile behaviour of both MMC conditions is strongly dependent on the matrix alloy and the trends with ageing condition are the same in the unreinforced alloy and the MMC. The MMC is sensitive to a surface damage/surface residual stress interaction and the mode of fracture is dependent on whether machining is carried out before or after heat treatment. A model has been proposed for the surface initiated fracture observed in MMC specimens machined after heat treatment. In the unreinforced alloy <IMG WIDTH=11 HEIGHT=11 ALIGN=BOTTOM SRC="/maths/***">K th decreased and region I crack growth rates increase with ageing, due to homogenisation of deformation at the crack tip as ageing progresses and the suppression of faceted growth. In the MMC, fatigue crack growth is insensitive to ageing up to the overaged condition because deformation is homogenised in all ageing conditions due to the reinforcement, small grain size and high dislocation density.

关键词： 纳米晶   磁性   Bg   微结构   土壤结构   Fe   Nd  

摘要： 纳米晶Ｎｄ－Ｆｅ－Ｂｇ合金的磁性与微结构熔体快淬Ｎｄ—Ｆｅ－Ｂ基合金带的微结构和磁性强烈地依赖于合金成分和快淬条件。传统工艺制造的合金带为各向同性微晶结构，晶粒尺寸处于５０～１００ｎｍ。这种材料具有高的矫顽力１Ｈｃ，但剩磁Ｊｒ小于Ｊ０／２（Ｊ．为饱和...