The Optical Properties of Light Rare-Earth Metals in the Liquid State

The model of almost free electrons is used to analyze the experimentally obtained optical properties of liquid light rare-earth metals (REM) such as lanthanum, cerium, praseodymium, and neodymium. The electrons involved in interband transitions are divided into different groups. In so doing, the contribution by these groups of electrons to the light conductivity is taken into account. The problem of determining partial values of functions is solved in a graphic representation using the method of successive approximations, by variational selection of three parameters, namely, the height of peak, its position, and half-width. It is demonstrated that, in order to explain the experimentally obtained dispersion curves of light conductivity of liquid lanthanum and cerium, it is sufficient to divide the electrons involved in interband transitions into no more than eight groups and, in the case of praseodymium and neodymium, into no more than nine groups. The electron characteristics of these groups of excited states are given.     

Surface Tension Measurements of Liquid Metals by the Quasi-Containerless Pendant Drop Method

The surface tensions of liquid metals, Zr, Ni, Ti, Mo, and Nb, have been measured at their melting points using the quasi-containerless pendant drop method. This method involves melting the end of a high-purity metal rod by bombardment with an electron beam to form a pendant drop under ultrahigh-vacuum conditions to minimize surface contamination. The magnified image of the drop is captured from a high-resolution CCD camera and digitized using a frame-grabber. The digital image is analyzed by reading the pixel intensities from a graphics file. The edge coordinates of the drop along rows and columns of pixels are searched by a computer program and stored in an array. An optimized theoretical drop shape is computed from the edge coordinates by solving the Young–Laplace differential equation to deduce the surface tension. The measured surface tensions are compared with available experimental results and theoretical calculations.     

The Law of Corresponding States and Surface Tension of Liquid Metals

Empirical relationships for the surface tension of liquid metals (LM) are shown to follow from the principle of corresponding states. In order to relate the surface tension of LM to its bulk properties, a formula is derived by scaling with the melting point T _m (0) at the atmospheric pressure, p = 0 and the atomic volume _m (0) at the melting point as macroscopic parameters for scaling and a characterizing the interatomic potential (r)= *(r/a). Correlation rules, derived for the surface tension and its temperature coefficient, are discussed and compared with experimental data.     

Fusion Equation of Metals

An expression of initial slope of meltingcurve of pure metals was obtained as follows:(dT_m/dP)_o=T_(mo)/c, where c=1.09 (N_(at))~(5/3)z~(-1/3),the unit of c is GPa, N_(at) is the atomic concentra-tion (in 10~(28) m~(-3)), z is the valence, T_(mo)is the melting temperature (in k) of metal underone atmosphere. The calculated results forthirty-one metals agree well with experiments.It has also been proved that by using the freeelectron model of melting, the fusion equationof metals is Simon equation (T_m/T_(mo))q=1+(p/d).Two parameters q and d, which have to fit withexperiments in Simon's empirical equation, nowcan be predicted theoretically, e.g. for Mg,giving q=1.56, d=7.88GPa, the calculated meltingcurve in a fairly wide pressure range (0～60GPa)is shown to be close to the experimental one.     

316L不锈钢选区激光熔化成型非水平悬垂面研究

为了提高选区激光熔化直接成型非水平悬垂面的能力,通过实验研究了影响悬垂面极限成型角度的工艺因素.实验使用316L不锈钢粉末,设计了不同倾斜角度的悬垂平面模型和悬垂曲面模型.结果表明:提高预置粉末密度可以提高悬垂面成型的极限角度;在25 μm的成型厚度下,激光扫描能量输入在0.15～0.2 J/mm时悬垂面成型精度最高,...     

锻造技术在轻金属中的应用

随着社会的发展,材料的研发与设计向着轻量化、高强化发展,轻金属在航空航天以及汽车工业上表现出了良好的应用潜力,同时也对材料加工成形方式,如锻造技术等提出了更高的要求。简要介绍了金属锻造技术,如自由锻造、等温锻造和多向锻造技术,分析了锻造技术在轻量化金属如钛合金、铝合金以及镁合金上的应用,经过锻造处理后,金属的微观组织及力学性能得到了提升,锻件质量得到了改善。还介绍了数值模拟在锻造过程中模具设计及工艺优化上的研究及应用现状,同时对金属锻造未来向精密化、复杂化以及智能化的发展趋势进行了分析与展望。     

轻金属材料在核反应堆中的应用

元素周期表中与氢同族或相近的轻金属元素（Li、Be、Na、Mg、Al）及其合金具有中子吸收截面小,感应放射能小等核学性能优点,可做为核裂变、聚变反应堆中包壳、慢化剂、中子源、冷却剂、氚增殖等部件材料,本文对这些轻金属材料在核领域中的应用进行概述。     

Viscosities of Multicomponent Silicate Melts at High Temperatures

In the present work; the viscosities in the quaternaries CaO–Fe _n O–MgO–SiO₂, Fe _n O-MgO–MnO–SiO₂, and CaO–MgO–MnO–SiO₂ and the quinary CaO–Fe _n O–MgO–MnO–SiO₂ were studied. The experimental technique employed was the well-established rotating cylinder method, using a Brookfield digital viscometer mounted over a specially designed graphite furnace. Generally, iron crucibles were used along with iron spindles. Periodic calibrations of the experimental setup were made using the standard reference slag recommended by the European Union. The measurement's were carried out up to a maximum temperature of 1773 K in all cases. The reliability of the measurements were checked at different rotation speeds as well as during thermal cycling, and excellent reproducibility of the results was noted. The experimental viscosity values were incorporated into a viscosity model. Equations based on the model for calculating the viscosities of the quarternary systems CaO–Fe _n O–MgO–SiO₂, Fe _n O–MgO–MnO–SiO₂, and CaO–MgO–MnO–SiO₂ and the quinary system CaO–Fe _n O–MgO–MnO–SiO₂ are provided.     

Localized Surface Plasmon Resonance Enhanced Light Absorption in AuCu/CsPbCl3 Core/Shell Nanocrystals

Localized surface plasmon resonance (LSPR) is shown to be effective in trapping light for enhanced light absorption and hence performance in photonic and optoelectronic devices. Implementation of LSPR in all-inorganic perovskite nanocrystals (PNCs) is particularly important considering their unique advantages in optoelectronics. Motivated by this, the first success in colloidal synthesis of AuCu/CsPbCl₃ core/shell PNCs and observation of enhanced light absorption by the perovskite CsPbCl₃ shell of thickness in the range of 2–4 nm, enabled by the LSPR AuCu core of an average diameter of 7.1 nm, is reported. This enhanced light absorption leads to a remarkably enhanced photoresponse in PNCs/graphene nanohybrid photodetectors using the AuCu/CsPbCl₃ core/shell PNCs, by more than 30 times as compared to the counterparts with CsPbCl₃ PNCs only (8–12 nm in dimension). This result illustrates the feasibility in implementation of LSPR light trapping directly in core/shell PNCs for high-performance optoelectronics.     

Principles of Ultrasonic Treatment: Application for Light Alloys Melts

Scientific and practical aspects of ultrasonic treatment of light alloy melts followed with development of acoustic cavitation in liquid metals are discussed. It is shown, that the ultrasonic melt treatment raises the rate of degassing and fine filtration of light alloy melts and very strongly effects ingot structure. Furthermore, an inherited effect of ultrasonic melt treatment on the structure and properties of wrought light alloy semis is shown.     

Characteristics of Localized Plasticity Autowaves and the Debye Parameter in Metals

Technical Physics Letters - A correlation between the characteristics of localized plasticity autowaves and the Debye temperature of crystalline lattice in 19 metals has been analyzed. It is shown...     

聚碳硅烷熔体的稳态流变性能

采用自制装置对聚碳硅烷(PCS)熔体进行预处理。通过预处理获得三种不同分子量的PCS,并对其进行物理化学和稳态流变性能测试。结果表明,预处理后的PCS其数均分子量为1000 g/mol~1400 g/mol,属低聚物。在温度范围240℃~260℃和剪切速率范围0.001 s-1~10 s-1内有明显的剪切变稀现象。在测试的温度范围内,剪切变稀区的非牛顿指数随温度升高先减小后增大。预处理后的PCS粘流活化能为120 kJ/mol~180 kJ/mol,比一般高聚物的高得多。     

High Spatial Resolution Mapping of Localized Surface Plasmon Resonances in Single Gallium Nanoparticles

Plasmonics has emerged as an attractive field driving the development of optical systems in order to control and exploit light–matter interactions. The increasing interest around plasmonic systems is pushing the research of alternative plasmonic materials, spreading the operability range from IR to UV. Within this context, gallium appears as an ideal candidate, potentially active within a broad spectral range (UV–VIS–IR), whose optical properties are scarcely reported. Importantly, the smart design of active plasmonic materials requires their characterization at high spatial and spectral resolution to access the optical fingerprint of individual nanostructures, attainable by transmission electron microscopy techniques (i.e., by means of electron energy‐loss spectroscopy, EELS). Therefore, the optical response of individual Ga nanoparticles (NPs) by means of EELS measurements is analyzed, in order to spread the understanding of the plasmonic response of Ga NPs. The results show that single Ga NPs may support several plasmon modes, whose nature is extensively discussed.     

高能束表面改性技术的研究现状及发展趋势

随着现代工业的发展,各行业对高性能涂层和高效环保加工工艺的要求越来越高。高能束表面改性技术是一种新型的表面改性技术,可以获得综合性能优异的涂层,具有能量密度特别高、非接触式加热、热影响区小、对工件基材的性能及尺寸影响小、工艺可控性强、便于计算机控制、环保等优点。高能柬表面改性技术包括了激光表面改性技术、电子束表面改性技术、离子注入表面改性技术、高密度太阳能表面改性技术。本文介绍了各种高能束表面改性技术的原理、应用现状和发展趋势。综述了高能束表面改性技术作为一种绿色环保技术,不会造成环境污染,拥有极大的发展潜力和经济效益,国内外都在积极的进行研究,以便得到综合性能更好的涂层,推动表面技术的发展。     

光脉冲在半导体光放大器中传输理论模型的改进

阐明了在研究半导体光放大器对光脉冲放大这一动态过程中通常采用常数载流子寿命近似这一处理方法是不理的。通过考虑放大器中载流子的实际复合机制，数值模拟了脉冲数据流通过放大器后脉冲的时域分布，并与采用常数载流子寿命近似所得的结果进行了比较。结果表明，二者具有明显的差异。     

Determination of Rare-Earth Metals in Magnesium Alloys by Atomic Emission Spectrometry with Inductively Coupled Plasma

Measurement Techniques - An analysis technique for the determination of rare-earth metals Ce, Er, Gd, La, Nd, Y in magnesium alloys by the method of atomic emission spectrometry with inductively...     

材料的屈服应力和延伸率

本文根据材料学、力学、热力学以及物理学的基本知识,推导出了材料和压力加工等学科领域中的两个重要难题,即材资的屈服应力和延伸率的理论解析式。由此可以计算任何材料的屈服应力和延伸率,且理论值与实测值吻合较好。该研究改变了材料的屈服应力和延伸率只能凭实验确定的局面。因此,对于材料学和机械学的力能分析以及机械结构设计,具有重要的指导意义。     

玻璃熔制过程耗热的计算与测量研究进展

随着地球资源的日益枯竭,世界环境的不断恶化,绿色制造已成为中国乃至世界经济发展的必然选择。玻璃制造业是能源密集型产业,在平板玻璃制造的全过程中,熔化和澄清阶段能耗占全部能耗的一半以上,因此,熔化和澄清是玻璃工业节能研究的关键领域。本文概述了玻璃熔制能耗的计算与测量方面的研究进展,总结了其成果,分析了其局限性,并就以后科研工作和实践探索的方向提出几点建议。     

Surface Tension and Viscosity of Succinonitrile– Acetone Alloys Using Surface Light Scattering Spectrometer

Using a surface light scattering spectroscopic technique, the surface tension and viscosity of pure succinonitrile (SCN) and SCN–acetone alloys at 0.86, 1.69, and 2.25 mol% have been determined. The surface light scattering technique, and the procedures used for making the alloys and measuring their concentrations, are presented. Analysis indicates our interfacial surface tension and viscosity measurements have an uncertainty of ±2% and ±10%, respectively. The surface tension and viscosity were measured at various temperatures yielding relations among surface tension, viscosity, temperature, and concentration in SCN–acetone alloys.