Organization and trends in materials science and engineering education in the US and Europe

Materials education in the United States and Europe is today provided to students by a wide range of departments, programs and institutes. Only a small fraction of these are what we term “core MSE” departments. These departments practice the discipline of MSE, providing undergraduate and graduate education in, and carrying out research on, the four elements of the field and their interrelations. The elements are structure, processing, properties and performance. Viewing this MSE as a discipline (while simultaneously as a part of a larger discipline) provides new directions for, and freedom in, curriculum reform. It also provides a framework for developing a focus for our research efforts and guiding their direction.     

Visualization and Animation in Manufacturing and Materials

Scientific visualization is the application of modern techniques in computer graphics to make the results of science and engineering studies more effective. Visualization allows the researcher to take in a large quantity of data at a single glance, developing an understanding of the data and the relationship between factors that would be difficult to obtain with a more conventional presentation. The addition of animation provides even greater power, enabling one to better understand the changes that occur over time.     

Self-Diffusion in Grain Boundaries and Dislocation Pipes in Al,Fe, and Ni and Application to AlN Precipitation in Steel

Diffusion along microstructural defects, such as grain boundaries or dislocation pipes, is significantly faster than diffusion through an undisturbed crystal. The ratio of diffusion enhancement is 3-4 orders of magnitude close to the melting point and reaches up to several ten orders of magnitude close to room temperature. An assessment of literature shows a large scatter in the available data and emphasizes the need for representative mean values. Applying a least mean square fit to selected experimental information delivers temperature-dependent functions for the ratio of grain boundary and dislocation pipe to bulk diffusion, respectively. We demonstrate that application of the attained results in a computational framework for the kinetics of precipitation makes the predictive simulation possible for the evolution of particles located at dislocations and grain boundaries.     

近3年来日本钽铌进出口状况

总结了亚洲金属网公布的有关日本2003年、2004年及2005年1月-5月钽铌原料与制品的进出口统计数据．分析了日本钽铌市场的状况。预计2005年日本钽的总需求量为331t,同此下降6．5％     

数控车间DNC与MES集成技术研究与系统开发

数控车间DNC系统是设备层信息化管理的一种典型网络结构,而生产管理层常用的MES系统需要完善的车间现场信息才能有效运行,所以有必要进行DNC系统和MES系统的集成,实现企业管理层与设备层之间的信息交换.提出了一种数控车间DNC与MES的集成模型,构建了系统的通信网络,在此基础上设计了系统软件,实施了INTEG-DNC与某重工集团MES系统集成项目,证明了该模型和网络结构的有效性.     

日本Nb基超合金和复合材料研究新进展

介绍了日本近年进行的一项旨在替代Ni超合金、将燃气轮机进气温度提高到1500℃的高温材料研究项目。该项目以难熔金属中密度小、室温塑性好的Nb为基材，通过固溶强化和复合弥散强化改善合金的高温强度和韧性，通过多层膜和梯度组成膜进行抗氧化性和耐蚀性的表面改性，收到了较好的成效。通过6年的努力，研制成功了具有较高高温强度的Nb基固溶体合金(Nb-W-Mo系)和Nb基复合材料(Nb-W-Mo-Si-HfC系)，其力学性能好，抗氧化性的研究也取得了突破性进展。     

Relative porosity in aluminium and in aluminium alloys

Abstract

Pores are readily formed in aluminium alloy castings. Density and porosity area fraction are often used quantitatively to evaluate the quality of aluminium alloy castings. This study used the relative porosity, the ratio (d _c ? d _r)/d _c, where d _c is the density of the chilled sample and d _r is the density of the reduced-pressure test sample, to evaluate the quality of aluminium and Al–6Si and Al–13Si alloys. The bursting of degassing bubbles on the free surface of the melt brought debris of oxide particles into the melt, which were eventually trapped in the castings after pouring. These particles were accompanied with air pockets and/or engulfed by bubbles, resulting in pores shown on the sections of poured castings.     

Entropy and magnetocaloric effect in ferromagnets and antiferromagnets

Analytic expressions for the entropy of a ferromagnet and an antiferromagnet that make it possible to calculate the magnetic-field dependence of the entropy in a wide temperature range have been obtained in the mean-field approximation for the Heisenberg model. It has been shown that for Fe, Ni, and Gd the calculated magnitude of the magnetocaloric effect is in satisfactory agreement with experiment. The results of calculations of the dependence of the entropy of an antiferromagnet on the magnitude and direction of a magnetic field have been discussed.     

聚合物淬火剂的细菌问题分析及对策

聚合物淬火剂由于其显著的优点应用日益广泛。但使用中往往会滋生细菌,不仅加速了聚合物淬火剂的老化,而且有加速工件生锈、影响环境卫生等弊病。聚合物淬火剂中细菌的滋生与所用聚合物和水的质量,淬火系统的循环状况,pH值,杂屑杂油以及空气中的细菌等因素有关。使用好富顿生物稳定的产品AquaQuench245是一个解决细菌滋生的最佳方案。     

Relaxation mechanisms and microstructure in glass and glass-ceramics

Two LAS (Li₂O–Al₂O₃–SiO₂)-type glass-ceramics and their parent glass have been studied by isothermal mechanical spectroscopy. These materials have the same chemical composition but the two glass-ceramics differ in microstructure: one is a ‘β-quartz’ glass-ceramic whereas the other one is of ‘β-spodumene’ type. The isothermal internal friction measurements performed in a frequency sweep [10⁻⁴–31.6 Hz] with an inverted torsion pendulum, submitted to subresonant forced oscillations, at temperatures between 93 and 820 K, have revealed several mechanical relaxation peaks. A single internal friction peak is observed in the glass sample whereas two peaks occur in the ‘β-quartz’ and ‘β-spodumene’ glass-ceramics. A detailed microstructure analysis (XRD, IRTF, SEM, TEM and DTA) and dielectric loss measurements have allowed to interpret these relaxation phenomena. The mechanical relaxation peak observed in the glass (290 K for 1 Hz) is assigned to the stress-induced movement of lithium ions. In each glass-ceramic the ‘low-temperature’ peak (340 K for 1 Hz) is linked with the ion mobility in the respective main crystalline phase. As for the ‘high-temperature’ peak, its origin is totally different for the two glass-ceramics; in the ‘β-quartz’ glass-ceramic it is due to the Mg²⁺ and Zn²⁺ ion relaxation in the crystalline phase, whereas in the ‘β-spodumene’ glass-ceramic it is linked with a complex entity within the residual vitreous phase.     

焊接领域的标准化及合格评定--现状与未来

0概述 1994年4月15日的摩洛哥古城马拉喀什成为了世人瞩目的焦点,在这里举行的关贸总协定乌拉圭回合部长会议,做出了一个里程碑式的决定--成立世界贸易组织.会议签署了著名的关贸总协定,该协定所包含的"贸易技术壁垒协议"(TBT协议)对国际标准的产生、发展及应用产生了深刻影响.     

仿真技术及其在磨削加工中的应用

本文介绍了建模与仿真的基本概念，着重阐述了仿真技术在磨削加工中的应用，并展望了仿真技术的发展趋势。