GH4169合金的X射线荧光光谱分析

采用x射线荧光光谱仪测定GH4169合金中的锰、硅、镍、铬、钼、铝、钛、铌。研究了测量条件及基体 吸收—增强效应的校正。还时测量精度进行了研究,各元素的相对标准偏差分别为0．0466％～O．6777％。与 化学分析结果对照结果良好。     

选择溶解条件--ICP-AES法测定铝合金中10元素

在铝合金中,对常量、微量、痕量元素等的测量,传统上采用化学的方法来分析,手续繁杂,分析时间 亦长,有时不能满足大批量快速分析的要求。ICP-AES分析法,以其优异的分析性能被广泛应用于各种材料 的主要、次要,痕量、超痕量多元素的同时分析。但是,影响等离子炬状态的因素很多,只有在最佳工作状态下 操作,才能充分发挥ICP光源的优越性。     

表征PAN纤维和炭纤维微细结构的HRTEM样品制备方法

为用高分辨透射电子显微术(HRTEM)表征聚丙烯腈(PAN)纤维和炭纤维的微细结构，从纤维性能出发，探讨研碎、离子束减薄和超薄生物切片三种制备方法及其工艺步骤，结合实验结果，对比了三种制备方法的原理、优缺点，提出了制备方法的适用范围和选择原则，并推断适于表征预氧化纤维微细结构的样品制备方法。与生物样品的制备方法类似，把超薄生物切片法引入到纤维材料HRTEM样品制备领域，为系统研究炭纤维微细结构的演变提供了线索。     

Finite element simulations of crack propagation in functionally graded materials under flexural loading

Cracks in stepped and continuously graded material specimens under flexural loading were investigated via finite element analysis. Calculation of mechanical energy release rates and propagation angles with crack-opening displacement correlation and the local symmetry (K_II = 0) criterion, respectively, provided results most efficiently and accurately, as compared with compliance and J-integral approaches and other deflection criteria. A routine was developed for automatic crack extension and remeshing, enabling simulation of incremental crack propagation. Effects of gradient profile and crack geometry on crack-tip stresses and crack propagation path are examined, and implications of these for optimal design of graded components against failure by fast fracture are discussed.     

Calibration of the Weibull stress scale parameter, σu, using the Master Curve

This work proposes that the Weibull stress scale parameter, σ_u, increases with temperature to reflect the increasing microscale toughness of ferritic steels caused by local events that include plastic shielding of microcracks, microcrack blunting, and microcrack arrest. The Weibull modulus, m, then characterizes the temperature invariant, random distribution of microcrack sizes in the material. Direct calibration of σ_u values at temperatures over the DBT region requires extensive sets of fracture toughness values. A more practical approach developed here utilizes the so-called Master Curve standardized in ASTM Test Method E1921-02 to provide the needed temperature vs. toughness dependence for a material using a minimum number of fracture tests conducted at one temperature. The calibration procedure then selects σ_u values that force the Weibull stress model to predict the Master Curve temperature dependence of K_Jc values for the material. At temperatures in mid-to-upper transition, the process becomes more complex as fracture test specimens undergo gradual constraint loss and the idealized conditions of high-constraint, small-scale yielding assumed in E1921-02 gradually degenerate. The paper develops the σ_u calibration process to incorporate these effects in addition to consideration of threshold toughness effects and the testing of fracture specimens with varying crack-front lengths. Initial illustrations of the calibration process for simpler conditions, i.e. 1T crack-front lengths, use the temperature dependent flow properties and a range of toughness levels for an A533B pressure vessel steel. Then using the extensive fracture toughness data sets for an A508 pressure vessel steel generated recently by Faleskog et al. [Engng. Fract. Mech., in press], the paper concludes with calibrations of both m and σ_u over the DBT region and assessments of the Master Curve calibration approach developed here.     

离子束辅助沉积铌提高铀的抗腐蚀性能研究

利用离子注入技术在铀表面进行了离子束辅助沉积铌和离子注入铌形成表面改性层，并对改性层的厚度、注入元素的分布进行俄歇电子能谱（AES）分析和表面相及结构的X射线衍射谱（XRD）分析，用电化学极化法测试抗腐蚀性能。结果表明：离子束辅助沉积表面改性层比离子注入表面改性层明显增厚，铀的耐蚀性得到进一步改善。最后讨论了注铌改性层耐蚀性提高的原因。     

无损检测用加速器束流稳定性分析系统的研制

介绍了单道脉冲幅度分析系统对电子直线加速器每个宏脉冲内产生的电子束流稳定性的实时测量方法和对打靶产生的X射线剂量率进行动态监测的分析处理系统的研制与开发。介绍了单道分析器的原理和硬件组成。后端软件使用面向对象的Visual C^ .net开发完成，软件采用图形化软面板，所有控制和结果显示在计算机屏幕上。系统具有可靠性好、精度高、测量直观、应用软件的界面友好等优点。     

离子束辅助沉积立方氮化硼的试验研究

运用离子束辅助沉积(IBAD)法在硅片上制备了立方氮化硼(c—BN)薄膜，研究了辅助能量、辅助束流及辅助束中氮气含量等参数对膜中c—BN含量的影响。用红外光谱(FTIR)及X射线光电子能谱(XPS)分析技术对得到的c—BN膜进行了分析。结果表明：合适的离子辅助能量能够获得c—BN含量高的薄膜；膜中c—BN的含量随辅助气体中N2含量的提高而增加；辅助束流对薄膜的形成影响不明显。     

电容式两相流层析成象系统仿真研究

以油料在管道中输送为例进行电容层析成象仿真.利用有限元方法对电场建立数学模型,在SGI indigo 2 工作站上,使用AVS可视化软件和反投影算法,对3种典型流态模型反演及显示其流体成份分布的图象.