激光加热基座晶体生长——提高氧化物超导体材料临界电流密度的工艺途径

本文简要介绍激光加热基座晶体生长技术的基本原理，主要工艺特点及其在多种高熔点氧化物晶体生长中的应用，尤其是在高Ｔｃ氧化物超导体材料提高临界电流密度（Ｊｃ）方面所取得的重要成果．     

Fe-25Mn—5Al-0.2C合金低温电阻率的负温度系数行为

在4.2K到300K之间,在大块晶态Fe-25Mn-5Al-0.2C合金中观察到了反常的电阻负温度系数行为,在50K以下,电阻率大体和lnT成正比,可能起源于磁性的机制。 关键词：     

一种快速凝固AB2型储氢合金的球磨改性

通过熔纺（melt-spinning）法制备了Zr0.9Ti0.1（Ni0.57V0.1Mn0.28C0.05）2.1合金，并与C03Mo混合球磨以改善其动力学性能结果发现，经过球磨，储红合金与作为催化剂的Co3Mo接触更加紧密，电化学容量和活化性能得到明显改善交流阻抗测试表明，球磨大大改善了合金的表面活性．但长时间的球磨可使合金进一步非晶化，导致容量及活性的下降．实验结果还表明，将快速凝固合金与具有电催化作用的Co3Mo球磨得到的电极材料，其活性要高于合金与只作为导体的铜粉进行球磨或在无添加剂条件下进行球磨得到的电极材料．     

用于半胱氨酸检测的电化学生物传感器研究进展

半胱氨酸(Cys)作为人体重要的非必需氨基酸之一,对蛋白质合成、渗透调节、解毒过程、神经系统功能和抗氧化过程均发挥着重要作用,近年来广泛应用于医学临床、食品加工和生化研究领域。因此,发展快速、准确检测半胱氨酸浓度的方法具有重要意义。本文简要介绍了半胱氨酸的基本知识以及半胱氨酸的传统检测方法,对半胱氨酸定量检测的电化学传感器的研制与应用进行了重点阐述,并对其发展前景进行了展望。     

一种快速凝固AB2型储氢合金的球磨改性

Zr0. 9Ti0. 1 (Ni0.57V0.1Mn0. 28Co0. 05 )2.1 alloy was prepared by melt-spinning and ball-milled with Co3Mo additive to improve its kinetic characteristics. It was shown that after 2 h milling the alloy exhibited a much improved activation performance as well as electrochemical capacity. Electrochemical impedance experiments also showed that ball-milling of the alloy with Co3Mo could improve the surface activity to a great extent. This can be attributed to the catalytic effect of Co3Mo, which had a much closer contact with the alloy powder after ball-milling, on hydrogen oxidation. However, long time milling could decrease the capacity gradually due to the further amorphization of the alloy. The experimental results also showed that the alloy ball-milled with electrochemically catalytic material such as Co3Mo exhibited a better activity than those milled without any additives or with a metal powder such as Cu acting only as a conductor.     

Fe-C合金中形变诱导动态相变的蒙特卡罗模拟

采用蒙特卡罗（MC）方法模拟了Fe-C合金在奥氏体-铁素体相变的平衡温度之上的形变诱导动态相变过程.通过建立合适的MC规则,在一个MC模型中同时实现了奥氏体-铁素体相变、铁素体-奥氏体逆相变以及奥氏体动态再结晶过程的模拟.同时,一个基于矢量变换的拓扑模型被嵌入此MC相变模型,用来跟踪由于塑性变形导致的晶粒形貌变化.在此基础上模拟分析了动态相变过程中铁素体的形成特点,讨论了由于相变、逆相变和动态再结晶交互作用所带来的影响. 关键词： 形变诱导动态相变 蒙特卡罗模型 动态再结晶 介观模拟     

Construction and mechanism analysis on nanoscale thermal cloak by in-situ annealing silicon carbide film

In recent years,there is a strong interest in thermal cloaking at the nanoscale,which has been achieved by using graphene and crystalline silicon films to build the nanoscale thermal cloak according to the classical macroscopic thermal cloak model.Silicon carbide,as a representative of the third-generation semiconductor material,has splendid properties,such as the high thermal conductivity and the high wear resistance.Therefore,in the present study,we build a nanoscale thermal cloak based on silicon carbide.The cloaking performance and the perturbation of the functional area to the external temperature filed are analyzed by the ratio of thermal cloaking and the response temperature,respectively.It is demonstrated that silicon carbide can also be used to build the nanoscale thermal cloak.Besides,we explore the influence of inner and outer radius on cloaking performance.Finally,the potential mechanism of the designed nanoscale thermal cloak is investigated by calculating and analyzing the phonon density of states(PDOS)and mode participation rate(MPR)within the structure.We find that the main reason for the decrease in the thermal conductivity of the functional area is phonon localization.This study extends the preparation method of nanoscale thermal cloaks and can provide a reference for the development of other nanoscale devices.     

电弧特性及其对熔池形貌影响的数值模拟

通过电弧模型与熔池模型耦合数值模拟,研究了氩弧和氦弧特性及其对SUS304不锈钢钨极惰性气体保护（TIG）焊熔池形貌的影响.通过比较氩弧和氦弧的温度轮廓线以及阳极表面电流密度和热流密度分布发现,氦弧的径向距离比氩弧收缩明显,导致更多热量传递给阳极.模拟了氩弧和氦弧下浮力、电磁力、表面张力和气体剪切力分别对熔池形貌的影响.结果表明：不论是在氩弧还是在氦弧下熔池中表面张力是影响熔池形貌的最主要驱动力.在氩弧下,影响熔池形貌的另一个重要的驱动力是气体剪切力,而氦弧下则是电磁力.由于电磁力引起的内对流运动增加了熔深,从而导致相同氧含量时氦弧下的熔深和焊缝深宽比要高于氩弧下的熔深和焊缝深宽比.随着氧含量的增加,氩弧和氦弧下的焊缝深宽比均先增加而后保持不变.焊缝深宽比的模拟结果与实验结果符合较好. 关键词： 氩弧 氦弧 电弧特性 熔池形貌     

MOLECULAR DYNAMICS SIMULATION ON LOW ANGLE GRAIN BOUNDARIES

Molecular dynamics simulation has been performed to investigate the microstructure and properties of low angle grain boundaries, employing the embedded atom method(EAM) type interatomic potential for Ni-Al alloy. The energies of the low angle grain boundaries with different dislocation densities were calculated, and the results indicate that the low angle grain boundary energy varies as a function of misorientation angle. The simulation was found in good agreement with the calculation on the basis of the dislocation theories in the low angle scale. The low angle grain boundary energy goes up with the increase of misorientation angle and tends to go down after reaching a maximum. An energy cusp exists when the misorientation angle increases further, but in this scale the dislocation theories are invalid for energy calculation due to the strong interaction of the dislocations at the boundaries. The simulation results also indicate that the microstructure of low angle grain boundaries can still be described as dislocations when the misorientation angle is larger than 10°.     

氢对22－13－5不锈钢室温下力学行为的影响

２２－１３－５钢是一种高强度极稳定的奥氏体不锈钢，将它置于１０ＭＰａ（１００个大气压）纯氢气中在３００℃充氢１４天，含氢量为６５±１ｐｐｍ。室温下力学性能测试表明：充氢后钢的强度提高，塑性指标不变；但室温下瞬态蠕变和短期应力弛豫行为，在可比条件下，变得更为强烈。用Ａｌｄｅｎ的可动位错密度理论，对实验结果作了定性分析，并对瞬态蠕变结果进行了定量的计算。结果证明，氢原子阻碍位错运动，使材料强度增加，同时也使材料的粘滞性增大。