Improving the reliability of metallic structures in service in the conditions with low climatic temperatures by efficient application of advanced methods of modification of the zone of the welded joint

The concept of investigations carried out to increase the reliability of metallic structures designed for operation in the conditions of low climatic temperatures is described. The worldwide tendencies in the investigation of the processes of the formation and fracture of materials and components at low climatic temperatures are analysed. The main methodological approaches, directed at ensuring high parameters of the service reliability of structures in low carbon, low alloy steels are outlined. The experimental data obtained in this area are analysed. The directions for further experimental and theoretical studies are indicated.     

某型内燃机铝合金活塞的金相检验

借助金相检验相关知识,对某型号内燃机活塞进行了宏观组织和显微组织分析。结果表明:活塞基体部位分散性孔洞为1级,集中性孔洞为1级;复合材料部位分散性孔洞为1级,集中性孔洞为1级;活塞试样组织中α固溶体较大,共晶硅呈短条状,部分呈小块状,初晶硅呈中等块状,略有聚集, 评定为3级;鱼骨状铁相夹杂物及针状铁相夹杂物不明显,铁相夹杂物评定为1级。     

金属纳米粉末的制备方法

纳米材料的科学价值和应用前景已逐渐被人们所认识，已被公认为21世纪的三大科技之一。本文系统地介绍了当前主要用于制备金属纳米粉末的方法。并对这些方法的制备过程、优缺点以及目前用这些方法制备的金属粉末的情况进行了介绍。指出了存在的问题和未来的发展方向。     

金属凝固微观组织数值模拟的研究进展

概述了目前国内外凝固微观组织数值模拟的研究进展,介绍了采用计算机进行微观组织模拟的几种主要方法,评述了当前所使用的物理数学模型的特点及局限性,指出了该领域目前面临的问题和未来发展趋势.     

Current State of the Theory of Metal Corrosion Inhibition

The general regularities of the action of metal corrosion inhibitors are analyzed. It is noted that the creation of inhibitors is a big scientific problem, requiring that achievements of many fields of physical chemistry be used. The limitations involved in application of adsorption inhibitors, whose theory of action has been developed most thoroughly, are considered. The importance and theoretical aspects of the development of composite materials and inhibiting hydrophilic monomers, that undergo polymerization following adsorption on metal surface, are discussed. The search for ways to manage the polymerization of inhibitors in thin adsorption layers can become a new efficient direction of corrosion inhibition. Special cases of inhibition, which cannot be rationalized in terms of the adsorption theory and which require that complexation be taken into account, are discussed. As the theory of corrosion inhibition develops, the scope of inhibitors expands. Besides the combination of cathodic protection with corrosion inhibitors, the latter are used more and more widely in conversion coatings and in water-borne paints. The strict technological and environmental requirements that are applied to inhibitors in this case do not prevent the progress of this scientific direction and do not diminish its prospects.     

纳米氧化铝的制备及应用进展

对近年来纳米氧化铝材料的各种制备方法及应用进行了综述。主要通过气相法、液相法和固相法,对纳米氧化铝的制备方法进行系统的阐述,并对其在陶瓷材料制备、材料表面改性、聚合物改性、复合材料制备以及功能材料等方面的应用进行了综述。不断开发纳米氧化铝材料的新工艺和新方法,对于纳米氧化铝的制备具有重要意义。不断开拓纳米氧化铝的应用领域,进而改善产品质量。最后,对纳米氧化铝的制备技术和应用领域的发展方向进行展望。     

金属Zr热力学性质的第一原理研究

应用基于密度泛函与密度泛函微扰理论的平面波赝势方法计算了一组不同晶格常数下hcp结构金属Zr的声子谱及相应的静态总能,由此得到不同晶格常数下的自由能,由准谐近似及自由能极小判据得到自由能与温度的关系,进而计算了金属Zr热膨胀系数、体弹性模量、定容及定压摩尔热容与温度的关系,计算结果在较宽的温度范围内与实验相符.对热膨胀系数,同时应用Debye-Grüneisen模型进行了计算,并与第一原理方法的结果进行了比较.对摩尔热容的计算考虑了电子的贡献,表明在高温区电子热容的贡献不能忽略.     

Fe对镁合金性能的不良影响及其对应措施

Fe是镁及镁合金中的有害元素。介绍了镁合金中铁相的形态及其对镁合金组织性能的影响．综述了含Mn、B、Zr、Ti等镁合金除铁剂的研究现状及消除和改善铁相形态的措施,分析了影响除铁效果的因素,指出了今后镁合金除铁的研究方向是高效并确保镁合金良好的综合性能。     

Survey of inclusions in twin roll casting of wrought aluminium alloys

Abstract

Spent filters employed in twin roll casting of wrought Al alloys were thoroughly analysed to identify the type of inclusions responsible for a variety of quality problems in Al sheet and foil. The inclusions are predominantly of the TiB₂, Al₂O₃ and MgAl₂O₄ variety. The former are invariably in the form of clusters and occupy a volume fraction relatively larger than that of oxides. The oxides entrapped inside the spent filter are mainly films with a lacy morphology and are accounted for by poor foundry practices. The angular oxide particles, 10 to 20 μm in size, are believed to be inherited from the electrolytic cells where primary Al is produced and from eroded refractory linings. There are occasionally dispersed carbide and halide salt particles retained inside the spent filter. Their volume fractions, however, are too small to generate Bragg reflections in the XRD analysis.     

Special features of metallurgical processes in plasma welding of chromium bronze

The metallurgical processes taking place in the weld pool in plasma welding of chromium bronze are investigated. The reasons for the formation of defects, hot cracks, and pores are determined, and measures that should be taken to prevent the formation of these defects are indicated.     

铝-稀土金属间化合物形成焓的计算

详细分析了二元铝-稀土金属间化合物的形成焓的Miedema计算值和文献报道数据的误差分布.结果表明,计算值相比于文献中实验数据普遍呈现负偏差.为此,计算研究中需要针对铝-稀土元素重要的影响因子--稀土原子与铝原子的半径比来修正热力学计算模型.对铝-稀土金属间化合物的系列计算结果及其误差分析说明,修正的Miedema模型计算值更加接近实验值,误差由原来的36%缩小到目前的5%.并利用MTDATA热力学计算软件部分验算计算结果,证明依据新模型的热力学计算预测更加准确可靠.用新模型计算了常见的铝-稀土金属间化合物的形成焓,同时也计算了Al-Er,Al-Tb,Al-Gd 等研究数据缺乏的铝-稀土金属间化合物的形成焓.     

机械加工和铁水孕育处理对球墨铸铁曲轴中频淬火裂纹的影响

曲轴中频淬火裂纹有油孔裂纺和轴颈表面裂纹两种。油孔淬裂的主要原因是油孔加工后的α值偏小；轴颈表面淬裂的主要原因是铁水熔炼的炉前孕育操作不良。     

TiSi(CN)系列涂层的结构和性能研究进展

近年来,随着工业的发展,机器零部件的应用面临了新的挑战,关键零部件的磨损腐蚀导致的涂层失效变得尤为显著。Ti基涂层因其低摩擦系数、硬度高、耐磨性好且具有优异的耐蚀性,逐渐受到了业界的关注。综述了物理气相沉积Ti Si C、Ti CN、Ti Si N和Ti Si CN硬质涂层结构和性能的研究现状。简要总结了Ti基涂层发展的历程,重点分析和对比了四种硬质涂层的成分、结构特点、硬度、结合强度、耐磨减摩性能和耐腐蚀性能,对于不同方法制备的涂层的影响因素分别做了分析,并对涂层的不同失效方式做了解释。从微观结构和性能两方面对涂层进行描述,阐明了硬质涂层中碳的键结构和相结构变化与涂层减摩自润滑性能之间的本构关系,指出了碳元素的石墨化转变在涂层减摩方面的重要作用。论述了钛基硬质涂层结构诱导超硬现象的机制,归纳和评估了超硬耐磨减摩涂层的特点。最后,对目前国内外Ti基涂层研究所存在的问题进行了总结,展望了物理气相沉积钛基多元多界面硬质涂层的发展方向和前景。     

Microstructure development during the deformation of aluminium-magnesium alloys

The conditions for serrated yielding in aluminium-magnesium alloys in temperature/strain rate space are reported. The microstructures of samples deformed just within and just outside the serrated regime are described. The differences in structure seen are relatively minor and do not seem to reflect the markedly different deformation behaviour. The conclusion is drawn that the deformed microstructures are formed, in part, by relaxation events after deformation and provide little evidence for the actual mechanisms of plastic deformation. Consequences for the development of alloys with good work hardening characteristics and good formability are discussed.     

大块非晶合金的研究历程

本文简述了大块非晶合金的发展过程和该领域的最新研究进展,并从成分结构条件、热力学条件、动力学条件等方面阐述了大块非晶合金的形成机制,介绍了目前常用的制备方法、大块非晶合金优异的性能和应用前景,并分析了其产业化的可行性。     

Calculation of thermodynamic properties of metastable phases of the elements

A chemical bonding model that provides a method of predicting thermodynamic properties of metastable structures of the solid elements is presented. The method involves a Born-Haber-type cycle to calculate the difference in bonding energies between the room temperature stable structures and metastable structures. To carry out the calculations, spectroscopic data are used to determine the promotion energies from the ground state of the gaseous atom to the valence state corresponding to each structure. Such data are available for most elements, but in cases where experimental data are lacking, they are derived using predictive models. Combinations of promotion energies and heats of sublimation are used to determine bonding enthalpies. The contribution of the outer-shell s and p-electrons and the inner-shell d and f electrons to the bonding energies are considered taking into account the crystal field effect upon the bonding abilities of different d and f orbitals This paper was presented at the Thermodynamics and Phase Equilibria of Metastable Phases Symposium at the Spring TMS Meeting, March 1-4, 1992, in San Diego. The symposium was organized by Philip Nash, Illinois Institute of Technology, and Ricardo Schwarz,Los Alamos National Laboratory.     

Effects of elastic interactions on the aggregation of nanostructures

Externally imposed fields can directly affect microstructural evolution arising from diffusional phase separation in binary mixtures and potentially can be utilized to form highly ordered nanostructures. The effects of elastic fields on phase separation and coarsening are investigated in this paper using a Cahn–Hilliard-type phase-field model. Periodic traction distributions are shown to lead to patterned microstructures. The kinetics and morphology of aggregation are found to depend significantly on the transformation strain, contrast in moduli between phases and the magnitude of externally applied tractions (mechanical fields). The trends observed in simulations are analyzed in detail in terms of Eshelby-type estimates for elastic interaction energies, and the correlations are shown to be remarkably accurate. Predictions based solely upon interaction energies can provide very useful guidelines to develop strategies to control the morphology of aggregation.     

环境试验与武器装备高新技术发展

论述了古代、近代和现代的科学技术与兵器的发展,并以高新技术兵器的发展为切入点,阐明了环境试验在武器装备设计、研制、生产、使用中的地位和作用,以及科技发展、武器装备发展对环境试验的需求关系和相互促进作用.最后就环境试验的现状提出了今后应奋斗的目标和任务.     

不锈钢水泵底架成形工艺及模具设计

分析了水泵底架原冲压成形工艺存在的问题,提出了新的成形工艺方案,介绍了新工艺中关键工序的模具结构以及模具加工、现场调试应注意的事项。经生产验证,改进后的工艺与模具结构合理,产品质量及生产效率大大提高。