从铝合金的应变时效内耗考察位错与点缺陷的交互作用

研究了合金含量、合金元素和形变条件对铝合金应变时效内耗行为的影响．由此描述了点缺陷的分布状态和位错组态；指出了控制应变时效回复过程的因素是溶质原子的动性和溶质原子与位错的作用能。提出了能描述应变时效过程中位错─—点缺陷交互作用的位错弦脱钉和位错气团拖曳共同作用的复合模型，相应的理论处理合理地解释了实验现象。 关键词：     

Dislocation-induced internal friction of a material with vacancies in weak magnetic field pulses

It is found that the form of the amplitude dependence of low-frequency internal friction in a quenched and aged aluminum sample (99.999% pure) changes under the effect of weak magnetic field pulses (H≥10⁵ A/m): the general level of internal friction increases. This effect is attributed to the influence of a magnetic field on the structural complex formed by a dislocation and point defects (the role of point defects is played by vacancies).     

Structural evolution of self-ordered alumina tapered nanopores with 100 nm interpore distance

We in-detail investigated the profile evolution processes of highly ordered alumina under the cyclic treatment of mild anodizing of aluminum foils in oxalic acid followed by etching in phosphoric acid. With the cyclic times increasing, the profiles of nanopores were gradually evolved into the parabola-like, trumpet-like and conical shape. Although the inserted etching itself nearly had no impact on the growth rate of the nanopores due to the rapid recovering of thinned barrier layer at the initial stage of next anodizing, overmuch etching could bring apparent side effects such as wall-breaking, thinning and taper-removing from the top down. The anodizing and etching kinetics and their synergetic effects in modulating different aspect ratios and open sizes of conical pores were studied systematically. These findings are helpful to tailor high-quality anodic alumina taper-pores with tunable profiles.     

Magnetic nanowires fabricated by anodic aluminum oxide template—a brief review

Anodic aluminum oxide(AAO) with highly ordered nanoscale pores which are monodisperse and mutually parallel can be produced through a self-organized electrochemical process.Subsequent deposition of materials into the nanopores produces AAO embedded nanowire arrays.Whilst the templates can be further removed to obtain free individual nanowires,the embedded nanowires form an interesting nanocomposite structure.Recent research activities on the fabrication and characteriza-tion of AAO template based magnetic n...     

Study on Fluorescence Characteristic of Quercetin–Nanoporous Anodic Aluminum Oxide Composites

Nanoporous Anodic Aluminum Oxide (AAO), its average diameters of porous were 50 nm, was obtained by two-step electrochemical anodization aluminum process. Highly ordered luminescence arrays formed by filling AAO nanopores with quercetin molecules has been studied by fluorescent spectroscopy in this work. AAO showed stronger adsorption capability of quercetin than Al³⁺-quercetin complex. The mechanism may be physical and chemical adsorption all together. Meanwhile, red shift of the maximum fluorescence peak of quercetin in AAO was observed. The molecular assemblies in the nanopore array are highly ordered and the fluorescence polarization dependence indicates a preferred molecular orientation along the pore axis. This maybe explains the mechanism of molecular luminescence depending on its environment.     

基于聚焦形貌测量的铝合金电弧增材制造件表面三维形貌重建

针对聚焦形貌测量提出了一种组合式的像素点清晰度评价算法。对于有序点云缺失点的插补,使用基于三次B样条的方法,来进行插补,通过实验证明该方法能够有效的补齐缺失点,以得到完整的点云数据。根据聚焦形貌恢复技术原理,搭建了一套完整的硬件,通过精度验证实验,测量设备在10X倍率下的测量精度在742.9nm。并对铝合金电弧增材制造件进行了表面形貌测量,可清晰观察其表面形貌,检测其缺陷。实验结果表明提出的方法兼具恢复的高精度性及有效性,应用此方法可以完成微观形貌的表面三维参数的测量分析。     

一种可控纳米柱阵列的研制

在一次阳极氧化法制备多孔氧化铝(anodized aluminum oxide,AAO)的基础上,进行了二次、三次、四次氧化制备AAO,并对多次氧化制备多孔AAO的电流变化曲线和模板表面的形貌特点等进行了比较分析.二次、三次、四次氧化制备的AAO纳米孔孔径依次增大、孔间距减小,而模板表面的纳米孔有序性分布没有明显变化.控制一次氧化AAO模板的除膜时间,～10 min即可得到孔径规则、高度有序的AAO膜.最后,利用所制备的不同孔深和孔径的AAO为模板,通过热纳米压印复制技术制备了长度和直径等性质可控的PMMA纳米柱阵列. 关键词： 纳米柱阵列 聚甲基丙烯酸甲酯 多孔氧化铝模板 多次氧化法     

二相介质中一种位错构型的弹性场及所受的力

本文建立了二相介质中与相界斜交位错的一种理想构型。根据位错各向异性弹性理论的普遍方法,以及关于界面的Gebbia-Eshelby定理,计算得到此位错在两相中的弹性场,以及位错线段所受“像力”的数值解。本文所提出的模型及算法具有一般适用性。结果可用于进一步计算此位错与其它缺陷的相互作用。对于考虑这种斜交位错在无扩散相变中的作用,本工作也是一个有意义的起点。 关键词：     

Nanoporosity of fine-crystalline aluminum and an aluminum-based alloy

The presence of nanopores formed during the equal-channel angular pressing of aluminum is revealed using small-angle x-ray scattering. The parameters of nanopores are determined, and a correlation between the level of nanoporosity and the fraction of high-angle grain boundaries is found. The data obtained indicate that the level of nanoporosity can affect the tensile durability of fine-crystalline aluminum in the creep mode. The data on the regularities in the development of nanopores under deformation of the fine-crystalline aluminum-based alloy in the superplasticity mode are obtained.     

Statistical mechanics of melting mediated by two types of defects

We propose a defect-mediated melting theory based on the statistics of two types of lattice defects, the point defects and dislocation pairs. The model predicts a first-order phase transition. Based on the model, phase transition temperature, latent heat and other thermodynamic functions are derived. Melting occurs due to discontinuous growth of point defects into dislocation pairs. The calculated phase transition temperature for five alkali metallic crystals are in fair agreement with measured melting temperatures, and the Richards' rule is derived by the model also.