关键词： Alloy 617   Hot deformation   Kinetic analysis   Processing map   Dynamic recrystallization   Microstructure  

摘要： The hot deformation behavior of alloy 617 has been studied by performing hot compression in a range of temperatures (1173-1473 K) and strain rates (0.001-10 s(-1)). The peak flow stress found to increase with Zener-Hollomon parameter (Z) following a hyperbolic-sine function relationship whereas peak strain followed power-law type relationship with Z. The average activation energy for the entire hot deformation domain was estimated to be 481 kJ mol(-1). The experimental stress-strain data has been used to develop processing map employing dynamic material model. The material exhibits a wide stable domain below 0.1 s(-1) spanning over 1250-1473 K, with a peak efficiency of similar to 45%. Based on the processing map and subsequent microstructural observation, the optimum hot deformation domain of alloy 617 is identified as 1323-1423 K and 0.001-0.1 s(-1). Furthermore, microstructural observation alone has revealed that a significant DRX with grain refinement could also be obtained at high temperature (>1373 K) and high strain rate (>1 s(-1)) domain although processing map has marked this region as unstable domain. (C) 2016 Elsevier B.V. All rights reserved.

关键词： 水化硬化机理   水泥基材料   构形   中国硅酸盐学会   南召   学术交流   物理力学性能   研讨内容  

摘要： 为了促进学科发展，充分发挥中国硅酸盐学会的学术交流优势和《硅酸盐学报》作为开展学术交流、学术争鸣重要阵地的作用，定于2016年8月14日～16日在山东省济南市举办水泥基材料水化硬化机理与微结构形成研讨会，研讨内容为：水泥基材料的组成、水化硬化机理、微结构形成及其与物理力学性能的关系。

关键词： 纳米复合   热电材料   PbSe  

摘要： 相比于常见的热电材料PbTe,另一种硫族铅化合物PbSe具有熔点高、Se储量更丰富等优势,从而越来越受到科学界的关注.本文采用熔融淬火结合快速热压烧结工艺制备了Pb_(0.98-x)Mn_xNa_(0.02)Se(0 ≤x≤0.12)纳米复合热电材料,系统地研究了不同Mn含量对材料微纳结构、机械性能和热电性能的影响规律.发现纳米复合样品中有面心立方结构的Mn Se球状和薄层状析出物,显微硬度得到显著增强.少量固溶的Mn增加了能带简并度,使功率因子提高,球状析出物使声子散射增强、热导率降低,体系的热电优值ZT得到优化;但是当Mn含量更高时,赛贝克系数趋于饱和,连续析出物使晶格热导率反常增大,ZT没有得到进一步改善.通过进一步调节Na含量优化了载流子浓度,获得了ZT=0.65的PbSe-Mn Se纳米复合热电材料.

关键词： 液晶显示   光学膜   表面微结构   背光   视角偏转  

摘要： 针对传统的液晶显示器应用于一些驾驶舱时存在的特殊观看视角问题,设计了一种新型的光学膜,以使液晶显示器的最大亮度可根据观看者的位置实现特定角度的偏转。首先,基于现有背光的配光曲线,提出光学膜表面微结构为直角三角形;考虑由于直角边的全反射,半光强视角范围较窄且存在截止角,对微结构进行了棱高和角度的优化设计,使半光强处视角范围得到提高。为消除截止角并进一步增大半亮度视角范围,对微结构再次进行优化设计,提出了双峰折线形非对称的光学膜表面微结构。仿真结果表明:水平视角不变时,偏转膜垂直方向最大亮度在20°处,透过率为87.3%,半亮度视角为(-12.5°,45°)。根据设计结果加工了实际样品并进行了实验测试,测试结果表明:与传统的背光视角相比,偏转膜垂直方向最大亮度由原来的0°偏转到18.9°,半亮度视角由(-24.1°,23.5°)变为(-9.2°,45.3°),透过率为82.0%,满足了特定视角的观看要求。

关键词： 人工微结构材料   电磁损耗   电磁性能  

摘要： 本文主要介绍了新型人工微结构材料中损耗对材料性能的影响.随着生产工艺和制备技术的提升,使新型人工微结构电磁材料获得了特殊的研究地位和研究价值.通常人工微结构材料的制备原材料都是取自于金属材料,而对于金属材料,损耗是不可避免的.那么损耗对微结构材料性能的影响成为人们关注的热点.通过研究材料电磁损耗的物理机制得出损耗虽然对电磁材料的应用带来负面效应,但是在特殊材料结构中损耗反而是有益的.将分析过程及结果渗透到本科物理学专业《电动力学》的实践课中,不仅拓宽了学生的知识面,而且提升了学生的创新能力.

关键词： magnetocaloric   Gadolinium   inclusions   selective oxidation   mechanical properties  

摘要： The development of advanced materials and technologies based on magnetocaloric Gd and its compounds requires an understanding of the dependency of mechanical properties on their underlying microstructure. Therefore, the aim of the study was to characterize microstructural inhomogeneities in the gadolinium that can be used in magnetocaloric refrigeration systems. Microstructures of magnetocaloric gadolinium cylinders were investigated by light microscopy and FE-SEM (Field Emission Scanning Electron Microscopy), EDS (Energy-dispersive X-ray Spectroscopy), and BSE (Back-scattered Electrons) in both the extrusion and the extrusion-transversal directions. XRD (X-ray Diffraction) analyses were performed to reveal the presence of calcium-and fluorine-based compounds. Metallographic characterization showed an oxidized and inhomogeneous microstructure of the cross-sections. The edges and the outer parts of the cylinders were oxidized more intensively on the surfaces directly exposed to the processing tools. Moreover, a significant morphological anisotropy of the non-metallic inclusions was observed. CaF inclusions act as active nucleation sites for internal oxidation. The non-metallic, Ca- and F-containing inclusions can be classified as complex calciumoxyfluorides. The solubility of Er and Yb in the CaF was negligible compared to the Gd matrix and/or the oxide phase. Lower mechanical properties of the material are a consequence of the lower structural integrity due to selective oxidation of surfaces and interfaces.

关键词： Metakaolin   Geopolymer   Heavy metal   Wastewater treatment   Adsorption kinetics  

摘要： The microstructural characterization and adsorption properties of metakaolin (MK) and alkali-activated metakaolin, known as geopolymer materials (GP) were investigated. The structure and properties of the metakaolin and obtained geopolymer were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. Furthermore, based on the analysis of adsorption efficiency, microstructure and mineral structure, the difference between geopolymer and metakaolin on the performance of immobilizing heavy metals have been discussed. The kinetics of adsorption can be represented by pseudo-second order equation. The results of lead ions adsorption experiments were best fitted by Freundlich adsorption isotherm for both investigated adsorbents. The highest removal efficiencies of alkali-activated material based on metakaolin was found 97.5% at pH 4 and metakaolin removal efficiencies was found 92% at pH 5.5.

关键词： Coincident site lattice   Grain boundary   Dislocation-density   Transgranular   Intergranular   Fracture  

摘要： The competing microstructural failure mechanisms of transgranular (TG) and intergranular (IG) fracture, in martensitic steel bicrystals with coincident site lattice (CSL) boundaries of Sigma 3 and Sigma 17b, have been investigated, using a dislocation-density-based crystalline plasticity formulation and a recently developed overlapping fracture method. A dislocation-density grain boundary (GB) interaction scheme was coupled within a dislocation-density based crystal plasticity formulation to investigate how different types of CSL GBs affect dislocation-density evolution, plastic deformation, dislocation pile-up formation, TG and IG fracture, and fracture toughness. The computational predictions indicate that the bicrystal, with a Sigma 3 boundary, transitioned from IG to TG fracture, with large dislocation density generation and plastic deformation on the TG fracture planes. Bicrystals with the Sigma 17b boundary failed due to inter granular fracture and rupture, with much lower, in comparison with the Sigma 3 boundary case, dislocation density generation and plastic deformation. These predictions, which are consistent with experimental observations, indicate that 13 boundary is resistant to IG fracture with a higher fracture toughness than the Sigma 17b boundary case. More significantly, the computational framework can potentially be used as a guideline for GB engineering for failure-resistant materials. (C) 2016 Elsevier B.V. All rights reserved.

关键词： 表面微结构   防污   中科院   海洋建筑物   海生物污损   机制   材料   宁波  

摘要： 海洋环境中多种污损生物，如藤壶、藻类、牡蛎、贻贝等在船舶外壳、海洋建筑物、养殖网箱等表面上无选择性地大面积粘附或沉积的现象很普遍。海生物污损会增加船底粗糙度引起船舶航行阻力增加、能耗与排放加剧，加速海洋设施、建筑等结构件污损腐蚀而显著缩短它们的寿命，导致养殖网箱、定置捕捞的网衣等网孔、管道堵塞，损坏海洋仪器、导致仪器传动机构失灵、信号失真、性能降低。海生物污损给船舶等海洋人工装备和设施造成严重的危害，用防污涂料保护是最有效的方法。

关键词： MICROSTRUCTURE   MATERIALS -- Mechanical properties   IRRADIATION   MECHANICAL models   CHEMICAL processes