Microstructures of magnesium oxychloride

The well-crystallized phases of magnesium oxychloride (MOC) cement have been described as scroll-tubular whiskers and compared to the tobermorite crystals for a long time. However, sporadic evidence of the acicular crystals without enough and consistent detail has befuddled researchers in the microstructural studies of the cement. With the modern technology and powerful computational capability, more detailed and clarified microstructure of the MOC crystalline phases including morphology, crystal habit, grain size, and elemental composition could be revealed. This paper reports the work on microstructural examination of MOC cement providing practical information for further study of the crystal structure of the different reaction phases. The experimental results show that the crystalline phases of MOC cement are in general needle shaped crystals with a granular surface and bundled in different forms. Imprints of bundled needle shaped crystal can also be scrutinized in the massive and dense microstructure of the cement paste with high compressive strength.     

Predictability of Eutectic Microstructures

The interphase spacings σ in the microstructures of most binary and pseudobinary “normal” metallic eutectics can roughly be quan- tified with regard to their respective solidification rates v according to a general relationship constant the constant being commonly between 10^?10 and 10^?11 cm^{3 ?1} The designation “normal” relates to similar degrees of undercooling of either phase on a plain-front solidification process at variance with anomaleous eutectics which solidify at different degrees of under- cooling in an uncoupled or weakly-coupled manner. The “constant”, however, is an individual value for each eutectic system. It is lowest for “simple” eutectics forming no intermetallic com- pounds and having low terminal solid solutions. The constant is raised for systems by 3 orders of magnitude or more if extensive terminal solid solutions are present. A closer fit for deliberate normal eutectics is presented in this pragmatic approach if the concentration differences between the terminal phases in eutectics ΔC_E [at%] are attributed to them as a square term according to λ² + · v · ΔC_E² = constant. The data based on this relation still show some scatter but they are grouping to distinct material families e. g. to Pb-, Ag- or Al-based eutectics. The remanent differences are estimated to disappear as soon as the relation is extended by the interdiffusion coefficient D according to as is confirmed in cases where reliable D values are available. These findings are in contrast to the current published theories on eutectic solidification. Suggestions are given where the bound- ary conditions have to be altered in order to attain full accord be- tween experiment and theory.     

光学微结构的超精密加工技术

微结构光学元件在光电产品及光通讯产品中的应用日益广泛，采用多轴超精密机床加工光学微结构，可达到亚微米级形状精度和纳米级表面光洁度的高精度水平，详细介绍了光学自由曲面及光学微结构的超精密加工技术，并开发了适合超精加工微型槽和微透镜列阵的刀具轨迹自动生成软件。     

Microstructures of electrodeposited CdS layers

Cadmium sulfide (CdS) thin films were electrodeposited on two conducting oxide substrates from aqueous solutions at temperatures between 30 and 90 °C. The as-deposited films were characterized using scanning electron microscopy, transmission electron diffraction, atomic force microscopy and Raman spectroscopy and were found to be crystalline at all temperatures. The microstructural development of the films is also discussed based on field emission scanning electron microscopy and atomic force microscopy studies. The composition of the films was found to be independent of the deposition temperature, with a slight difference in the Cd/S ratio on the different substrates.     

银钠米晶微结构的尺寸效应

对银纳米晶的系列样品进行了XRD微结构实验研究和计算。结合所得到的晶粒度和微结构参数发现纳米银晶粒组元中存在着晶格畸变；随着晶粒尺寸的变化，银钠米晶的微结构呈现出明显的变化，其晶格畸变与晶粒度有着比较密切的关系。     

Microstructures and mechanical properties of milled and continuously cast lead sheet Part 1 Microstructures

Abstract

Milled lead sheet exhibits a recrystallised microstructure, the grain size of which decreases with increasing copper content; copper is present as particles of ~1–5μm in length, formed from the initial needles or plates of the cast billet by spheroidisation, or by particle break-up during rolling. A comparison of materials produced by several manufacturers indicates that the copper distribution and final grain size are dependent on the thermomechanical history of the sheet. Direct method sheet exhibits a cast cellular structure within grains which usually extend through the full thickness of the cast sheet; copper is present as a fine dispersion (particles ~0·5 μm dia.) at cell boundaries. The copper distribution in both materials was stable with prolonged heating (100 h at 200°C), but some grain growth occurred in the milled sheet. It was not possible to obtain a fully dispersed eutectic microstructure at the eutectic composition; primary lead dendrites (or cells) were always present. This is thought to be a result of the difficulty of nucleating a copper particle in the very low copper concentration alloys used in this work.

MST/1065     

Deformation-induced Microstructures of High-Mn Austenite Steel

Deformation-induced microstructures of high-Mn austenite steel was investigated bymetallography,X-ray diffraction and SEM.The ε-martensite and slip-bands are deformation-in-duced on the{111} planes,and appear as thin straight laths with 60～80° alignment difference be-tween them.It was found that ε-martensite and slip bands are kinked at fcc twin boundaries with thekinked angle 35～40°.The bands of equilateral triangle in the microstructure of tensile deformationare presented.     

雾化沉积Al—Cu—Mg合金的显微组织

本文采用雾化沉积技术制备了大块Ａ１—Ｃｕ—Ｍｇ合金快速凝固材料，对沉积态和经挤压及热处理后的材料组织进行了观察和分析。结果表明基体呈全部等轴晶并存在少量显微孔洞是沉积态组织的主要特征。过饱和固溶体、时效析出相以及变形和热处理过程中形成的弥散相构成了材料的主要强化相。     

Fe-C-Cr合金定向凝固组织

对经定向凝固的共晶 Fe—2.94％C—29.1％Cr 合金及过共晶 Fe—3.12％C—35.9％Cr、Fe—2.80％C—33.1％Cr 合金的凝固组织作了研究。上述三种合金中的初晶及共晶碳化物均为(Fe,Cr)_7C_3它们都以小面状析出,其中初晶在与凝固方向垂直的截面上为六角形块。初晶碳化物在定向凝固时以六角形状进行包抄式的凝固,然后再从六角形壳向内凝固,最终生成完整六角形。随着凝固速度变小,初晶(Fe,Cr)_7C_3的截面尺寸及间距增大,且从实心的六角形棒变成空心的六角形棒。过共晶合金的液固两相区长度约为1.5mm。共晶合金凝固时,碳化物的形貌为不规则多边形棒,且在凝固速度大时,组织细小。上述三种合金,当凝固速度 R>2m/sec 时,液固界面将变得凹凸不平。     

X-Ray Luminescence of ZnO Whisker Microstructures

Technical Physics Letters - Morphology and the optical and luminescent properties of zinc oxide (ZnO) whisker microcrystal arrays grown on sapphire using gas-transport synthesis from zinc vapors in...     

掺钛类金刚石膜的微观结构研究

采用无灯丝离子源结合非平衡磁控溅射的方法,在模具钢及单晶硅基体上制备了梯度过渡的掺钛类金刚石（Ti-DLC）膜层,利用俄歇电子谱（AES）、透射电镜（TEM）、X射线光电子能谱（XPS）及X射线衍射（XRD）等手段对膜层的过渡层、界面及微观结构进行研究。结果表明：制备的膜层成分深度分布与所设计的基体/Ti/TiN/TiCN/TiC/Ti-DLC相吻合,在梯度过渡中不同膜层之间界面体现为渐变过程,结合非常良好;少量的Ti主要以纳米晶TiC的形式掺入到非晶DLC膜当中;所制备的膜层具有厚2.9μm、硬度高达25.77 GPa、膜/基结合力44 N-74 N。     

铁氧体吸收剂微观结构对性能的影响

考察了在不同温度煅烧后铁氧体吸收剂粉体的相结构和微观形貌及其在X波段复数磁导率.研究认为铁氧体粉体的微观结构特别是W相的含量对磁导率有显著影响,粉体的磁导率的实部和虚部均随着W相含量的提高而提高,同时频率特性良好.1200～1300℃煅烧后粉体主晶相为W相,此时粉体的复数磁导率比较理想,微波反射率测试也表明该粉体具有较好的吸波性能.     

直接淬火装甲钢的微观组织和性能

设计和冶炼了一种低碳低合金热轧后直接淬火装甲钢（ＤＱ钢），采用控轧和轧后直接淬火工艺生产钢板。对微观组织和抗弹性能进行了分析，并与ＧＹ４和ＧＹ５装甲钢进行对比。结果表明，热轧后直接淬火钢的变形奥氏体扁平形态保留至淬火组织中，转变后的板条马氏体细小；ＤＱ钢的背面强度极限与中碳ＧＹ４和ＧＹ５钢相当。用ＤＱ钢取代中碳装甲钢大幅度提高焊接性能并节约合金元素，并有望在舰船防护上得到应用。     

金属凝固显微组织的计算机模拟

应用计算机数值模拟技术研究金属凝固显微组织的形成规律是材料科学发展的重要前沿领域之一。文章对该领域的最新研究进展作了简要评述；重点介绍了作者发展的一个改进的MCA(modified cellular automaton)模型的特点以及应用该模型在合金凝固组织 数值模拟方面的一些主要工作。     

ITO薄膜的微结构表征及其组分特性

用直流磁控溅射法制备了氧铟锡(ITO)薄膜。采用XRD、TEM、XPS对薄膜的微结构和化学组分进行了测试分析。分析结果表明:制备的薄膜中,Sn元素已固溶到In2O3晶格形成了多晶ITO。延长退火时间,薄膜的结晶度增加,SnO被氧化为SnO2并逐渐达到饱和,薄膜表面先失氧后附氧,膜中氧空位含量先增加后减少。退火1h后,薄膜具有最低电阻率(6×10-4Ω.cm)和高可见光平均透射率(93.2%)。