A study of the corrosion properties of plasma nitrocarburized and oxidized AISI 1020 steels

Plasma nitrocarburized AISI 1020 steels were oxidized for 15, 30 and 60 min to evaluate their corrosion and microstructural properties. After plasma nitrocarburizing for 3 h at 570°C in a gas mixture comprising 85 vol.% N₂, 12vol.% H₂ and 3 vol.% CH₄, the compound layer composed of ɛ-Fe_2–3(N,C) and γ’-Fe₄(N,C) phases and the diffusion layer above the matrix were observed. The top oxide layer, consisting mainly of magnetite (Fe₂O₄) and hematite (Fe₂O₃) phases, forms after post-oxidation treatment at 500°C. However, the oxide layer was severely degraded by spallation as a result of increases in post-oxidizing time. The difference in corrosion resistance should be attributed to the thickness of the top oxide layer, which was governed by post-oxidizing time.     

稀土含量对喷熔层组织及耐蚀性的影响

本文通过在镍基自熔合金粉末中加入不同含量的稀土，研究了稀土含量对喷熔层组织及耐蚀性的影响规律及其作用机制。结果表明，在喷熔材料中加入适量稀土，可使喷熔层组织细化、晶界净化，从而使腐蚀过程中的表面活性点减少，耐蚀性提高。     

CoFeZrRE磁性薄膜微波电磁特性研究

研究在微波段具有高磁导率和大磁损耗的CoFeZrRE薄膜,采用射频磁控溅射工艺制备该类薄膜,探讨了工艺参数和薄膜厚度对CoFeZrRE薄膜结构和电磁性能的影响.重点研究了掺杂稀土元素的含量和种类对薄膜磁各向异性、饱和磁化强度等基本磁参量以及微波磁导率和磁损耗的影响.结果表明,重稀土元素（如Dy,Tb）提高微波磁损耗的效果更显著;CoFeZrRE类薄膜具有较高的微波磁导率和磁损耗（2 GHz处,μ＇和μ＂均高于200）,有望在微波吸收和抗电磁干扰领域获得广泛应用.     

定向凝固水平连铸多晶铜的动态本构方程

以带有同步组装技术的分离式Hopkinson压杆装置作为热模拟装置，采用基于MTS（Mechanical Threshold Stress）模型建立的FCC晶体结构的动态本构方程，确定了定向凝固水平连铸多晶铜动态本构方程参数，研究了其动态冲击特性，获得高温段（685K-1085K）的理论应力-应变曲线与实验曲线相当吻合，而在低温段（低于685K）的理论曲线与实验曲线出入较大。结果也表明定向凝固水平连铸多晶铜在485K和685K之间有一温度能使其回复能达到阀值。     

喷射成形与铸造7A60合金的微观组织对比研究

利用喷射成形技术制备了7A60合金。借助扫描电镜（SEM），透射电镜（TEM），X射线衍射（XRD）等手段研究了喷射成形与铸造7A60合金微观组织的特点。结果表明，铸造7A60合金的组织粗大，偏析严重。喷射成形7A60合金主要由细化的等轴晶组成，无明显偏析。与传统铸锭冶金工艺相比，喷射成形工艺大大提高了冷却速率，显著细化了7A60合金的微观组织。     

TiAl合金的电子束蒸发行为

建立了TiAl合金蒸发和沉积数学模型，采用活度系数体现溶池中不同组元的相互作用，影响组元蒸发速率的因素主要有元素饱和蒸气压和活度系数，计算值与试验值符合良好。研究结果表明，TiAl合金可以采用底部连续进给单一水冷铜坩埚通过电子束物理气相沉积得到。     

Nanostructured component fabrication by electron beam-physical vapor deposition

Fabrication of cost-effective, nano-grained net-shaped components has brought considerable interest to Department of Defense, National Aeronautics and Space Administration, and Department of Energy. The objective of this paper is to demonstrate the versatility of electron beam-physical vapor deposition (EB-PVD) technology in engineering new nanostructured materials with controlled microstructure and microchemistry in the form of coatings and net-shaped components for many applications including the space, turbine, optical, biomedical, and auto industries. Coatings are often applied on components to extent their performance and life under severe environmental conditions including thermal, corrosion, wear, and oxidation. Performance and properties of the coatings depend upon their composition, microstructure, and deposition condition. Simultaneous co-evaporation of multiple ingots of different compositions in the high energy EB-PVD chamber has brought considerable interest in the architecture of functional graded coatings, nano-laminated coatings, and design of new structural materials that could not be produced economically by conventional methods. In addition, high evaporation and condensate rates allowed fabricating precision net-shaped components with nanograined microstructure for various applications. Using EB-PVD, nano-grained rhenium (Re) coatings and net-shaped components with tailored microstructure and properties were fabricated in the form of tubes, plates, and Re-coated spherical graphite cores. This paper will also present the results of various metallic and ceramic coatings including chromium, titanium carbide (TiC), titanium diboride (TiB₂), hafnium nitride (HfN), titanium-boron-carbonitride (TiBCN), and partially yttria stabilized zirconia (YSZ) TBC coatings deposited by EB-PVD for various applications. This paper was presented at the International Symposium on Manufacturing, Properties, and Applications of Nanocrystalline Materials sponsored by the ASM International Nanotechnology Task Force and TMS Powder Materials Committee, October 18–20, 2004, Columbus, OH.     

稀燃车用催化剂的研究进展

稀燃车用催化剂是汽车尾气净化催化剂今后发展的方向，在稀燃条件下如何处理NOx是稀燃车用催化剂面临的巨大挑战。本文详细地评述了近年来国内外在这方面的研究工作，包括选择催化还原催化剂、存储还原催化剂和组合多功能催化剂的研究进展。     

A NEW ELECTROMAGNETIC IMAGING SCHEME

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The distribution of grain boundary planes in polycrystals

During the last ten years, techniques have been developed to measure the distribution of grain boundaries in polycrystals as a function of both lattice misorientation and grain boundary plane orientation. This paper presents a brief overview of the techniques used for these measurements and the principle findings of studies implementing these techniques. The most significant findings are that grain boundary plane distributions are anisotropic, that they are scale invariant during normal grain growth, that the most common grain boundary planes are those with low surface energies, that the grain boundary populations are inversely correlated with the grain boundary energy, and that the coincident site lattice number is a poor predictor of the grain boundary energy and population.