异种钢焊接接头熔合线附近块状铁素体的彩色金相鉴别方法

在对进口及国产受热面管T92-S30432异种钢焊接接头进行常规金相检验时发现,在T92钢侧熔合线附近有块状组织析出。采用先浅侵蚀再染色的复合彩色金相显微组织显示方法并结合显微硬度测度以及能谱分析等方法,对该块状组织进行定性分析以鉴别该块状组织。结果表明：采用该彩色金相显示方法得到显微组织的衬度和清晰度都较高,较好地弥补了黑白金相的不足,可以有效地鉴别出该异种钢焊接接头熔合线附近的块状组织为铁素体相。     

彩色金相

本文简要介绍了彩色金相技术的基本原理,讨论了在彩色金相摄影、洗印技术中加色法与减色法的应用,彩色胶片的色层组织及基本性能以及在实验中如何利用自动曝光装置来调整胶片的感光速度与伸缩性,合理使用滤色片来正确校正色温等问题。同时叙述了金相组织的着色上膜方法,推荐了常用的化学着色法中的五大类试剂。文章表明,实验中要想获得一张满意的彩色金相照片,必须满足下列三个条件:1.了解彩色金相技术的基本原理。2.掌握彩色胶片的基本性能和校正方法。3.正确使用显微组织的着色方法。     

铸铁偏析的彩色金相学研究

彩色金相技术是识别和鉴定金属中不同相的有力手段。鉴于目前彩色金相技术尚不能对材料的成分或成分偏析进行定量分析，将彩色金相技术与电子探针分析相结合，考察铸铁中硅含量与彩色金相颜色之间的变化规律。结果表明，彩色金相可以清晰地显示出铸铁中硅的偏析形貌及不同热处理条件下硅偏析程度的变化，并发现在铸铁彩色金相组织中两点之间的色序差与硅元素偏析度之间存在半定量的对应关系，即每一个色序差对应一定范围的偏析度，从而探索出用彩色金相技术半定量地分析铸铁中硅元素偏析的方法。     

合金钢中复相组织的彩色金相浸蚀方法

针对使用Lepera试剂进行合金钢彩色金相浸蚀容易失败的情况,对其具体操作步骤和注意事项进行了介绍和试验研究。结果表明:与普通金相浸蚀方法相比,该彩色金相浸蚀方法可以将合金钢中的马氏体/奥氏体岛组元、贝氏体组织和马氏体组织特征更为明显地显示出来,从而实现合金钢中复相组织的有效辨别。     

利用黑白金相设备开展彩色金相检验的探讨

介绍了利用金相实验室原有的设备进行彩色金相检验的方法。     

基于数字图像技术的彩色金相方法

利用数字图像伪彩色增强技术实现彩色金相,建立了金属相灰度级-伪彩色映射关系模型,并设计了在计算机上运行的金相伪彩色系统,使得输入的金相灰度图像中各相间微弱的灰度差转化为明显的色调差,显著提高了金相组织鉴别的衬度.     

铸态双相不锈钢彩色金相异常组织分析

采用金相分析、扫描电镜及能谱分析、X射线衍射分析、透射电镜分析以及显微硬度测试等方法研究了铸态2507双相不锈钢中各相的形貌和特征。结果表明:采用彩色金相侵蚀剂(1g偏重亚硫酸钠+10mL浓盐酸+50mL水)侵蚀后,彩色金相组织中的土黄色相为奥氏体相,黄绿色相为铁素体相,斑马纹状组织为(σ+γ2)共析组织。     

彩色金相在显微组织分析中的应用

介绍了彩色金相的显示原理、方法及在其显微组织分析中的应用,对比了双相钢、帘线钢彩色金相和黑白金相的显微组织颜色、形貌及定量计算结果。结果表明:彩色金相因其具有艳丽的色彩、强烈的对比度,可以明显辨识出双相钢、帘线钢各相显微组织,双相钢的铁素体组织呈浅黄色、马氏体和残余奥氏体呈亮白色、贝氏体呈棕黑色,帘线钢的珠光体呈亮白色,索氏体呈蓝、黑、棕、灰白等色,并能够计算出各相显微组织的面积分数,进而实现定量分析,其分析精度远高于传统黑白金相的。     

采色底片的减薄法

关于彩色底片的修正,有的将彩色底片经调整翻制制作彩色翻底片;有的将彩色底片的某一色调或全部色调进行减色;还有用染料将整个画面或部分画面进行染色等方法。下面只介绍减色的方法和减色液的配方。用减色法,可以调整彩色底片总密度偏     

NEOPHOT大型金相显微镜摄影成象系统改进成功

NEOPHOT大型金相显微镜具有设计合理、装置完善、制造精细、成象质量高、功能多、用途广等许多优点,因此是材料、工艺研究不可缺少的重要工具,仅航空航天系统就有数百台。但它也有一个突出的缺点,就是其摄影成象系统是单页底片(90×120mm),不能使用120或135胶卷进行摄影,更无法开展彩色金相技术的研究。而在当代,彩色金相已发展成为一项专门技术,由于它具     

Hierarchical stochastic homogenization analysis of a particle reinforced composite material considering non-uniform distribution of microscopic random quantities

This paper discusses a stochastic homogenization problem for evaluation of stochastic characteristics of a homogenized elastic property of a particle reinforced composite material especially in case of considering a non-uniform distribution of a material property or geometry of a component material and its random variation. In practice, some microscopic random variations in composites may not be uniform. In this case, a non-uniformly distributed random variation of a microscopic material or geometrical property should be taken into account. For this problem, this paper proposes a hierarchical stochastic homogenization method. This method assumes that a two-phase composite material can be separated into three-scales, and propagation of the randomness through the different scales can be evaluated with the perturbation-based technique. As an example, stochastic characteristics of homogenized elastic properties of a glass-particle reinforced plastic are estimated using the proposed approach. With the numerical results, importance of the problem and validity of the proposed method are discussed.     

基于耦合扩展多尺度有限元方法的功能梯度材料热应力分析

以高效模拟功能梯度材料(FGM)微观非均质性对整体热力学性能的影响为研究目的,通过随机形态描述函数(RMDF)法和体积分数的指数分布建立FGM二维微结构,在此基础上,发展了FGM热应力分析的耦合扩展多尺度有限元方法(CEMsFEM)。该方法基于扩展多尺度有限元方法(EMsFEM)的基本思想,对温度场和位移场构造数值基函数,以把微观非均质材料性质带到宏观响应中。同时为了考虑泊松效应导致的不同方向间的耦合作用,在位移场数值基函数中增加了耦合附加项。通过数值基函数建立宏微观单元信息的映射关系,在宏观尺度求解有效方程,节约计算量。为了更好地考虑微观载荷的影响,把结构的真实响应分解为宏观响应和微观扰动,进一步推导出修正的宏观载荷向量。通过不同体积分数分布的FGM在不同载荷工况下的热应力分析算例验证了本文中方法的正确性和有效性,最后讨论了微结构的尺寸效应对结构热力学响应的影响。     

A surrogate model for computational homogenization of elastostatics at finite strain using high-dimensional model representation-based neural network

We propose a surrogate model for two-scale computational homogenization of elastostatics at finite strains. The macroscopic constitutive law is made numerically available via an explicit formulation of the associated macroenergy density. This energy density is constructed by using a neural network architecture that mimics a high-dimensional model representation. The database for training this network is assembled through solving a set of microscopic boundary value problems with the prescribed macroscopic deformation gradients (input data) and subsequently retrieving the corresponding averaged energies (output data). Therefore, the two-scale computational procedure for nonlinear elasticity can be broken down into two solvers for microscopic and macroscopic equilibrium equations that work separately in two stages, called the offline and online stages. The finite element method is employed to solve the equilibrium equation at the macroscale. As for microscopic problems, an FFT-based collocation method is applied in tandem with the Newton-Raphson iteration and the conjugate-gradient method. Particularly, we solve the microscopic equilibrium equation in the Lippmann-Schwinger form without resorting to the reference medium. In this manner, the fixed-point iteration that might require quite strict numerical stability conditions in the nonlinear regime is avoided. In addition, we derive the projection operator used in the FFT-based method for homogenization of elasticity at finite strain.     

Structure–Property Relations in Carbon Nanotube Fibers by Downscaling Solution Processing

At the microscopic scale, carbon nanotubes (CNTs) combine impressive tensile strength and electrical conductivity; however, their macroscopic counterparts have not met expectations. The reasons are variously attributed to inherent CNT sample properties (diameter and helicity polydispersity, high defect density, insufficient length) and manufacturing shortcomings (inadequate ordering and packing), which can lead to poor transmission of stress and current. To efficiently investigate the disparity between microscopic and macroscopic properties, a new method is introduced for processing microgram quantities of CNTs into highly oriented and well‐packed fibers. CNTs are dissolved into chlorosulfonic acid and processed into aligned films; each film can be peeled and twisted into multiple discrete fibers. Fibers fabricated by this method and solution‐spinning are directly compared to determine the impact of alignment, twist, packing density, and length. Surprisingly, these discrete fibers can be twice as strong as their solution‐spun counterparts despite a lower degree of alignment. Strength appears to be more sensitive to internal twist and packing density, while fiber conductivity is essentially equivalent among the two sets of samples. Importantly, this rapid fiber manufacturing method uses three orders of magnitude less material than solution spinning, expanding the experimental parameter space and enabling the exploration of unique CNT sources.     

热得快火灾物证鉴定方法的研究

模拟热得快正常使用、通电过热、正常使用后受火灾作用和通电过热后受火灾作用,获得在不同试验条件下的热得快火灾残留物.用扫描电镜对热得快火灾残留物中的电热丝显微形貌进行了观察.结果表明,在不同试验条件下,电热丝的显微形貌有明显的不同.因此,利用扫描电镜,观察热得快电热丝的显微形貌,可以直观、快速地鉴别热得快在火灾前所处的状态,为热得快火灾原因的认定提供了一种新的技术方法.     

Dielectrophoretic segregation of different human cell types on microscope slides

A new method for preparing cells for microscopic examination is presented in which cell mixtures are fractionated by dielectrophoretic forces and simultaneously collected into characteristic zones on slides. The method traps cells directly from the suspending medium onto the slide, reducing cell loss. Furthermore, it exploits differences in the dielectric properties of the cells, which sensitively reflect their morphology. Because different cell types are trapped in characteristic zones on the slide, the technique represents an advance over existing methods for slide preparation, such as centrifugation and smears where cells are randomly distributed. In particular, the new method should aid in the detection of rare and anomalous cell subpopulations that might otherwise go unnoticed against a high background of normal cells. As well as being suitable for traditional microscopic examination and automated slide scanning approaches, it is compatible with histochemical and immunochemical techniques, as well as emerging molecular and proteomic methods. This paper describes the rationale and design of this so-called electrosmear instrumentation and shows experimental results that verify the theory and applicability of the method with model cell lines and normal peripheral blood subpopulations.     

Numerical simulation of the plastic flow properties of iron single crystals

Summary The present paper deals with the numerical simulation of the plastic flow properties of iron single crystals as well as their influence on the macroscopic elastic-plastic deformation and localization behavior affected by superimposed hydrostatic pressure. Based on experimental observations the onset of plastic yielding on the microscale is described by an extended microscopic yield condition taking into account various microscopic stress components acting on the respective slip systems. In addition, to be able to compute inelastic deformations from a plastic potential, the latter is expressed in terms of workconjugate microscopic stress and strain measures which leads to a non-associated flow rule for the macroscopic plastic strain rate. On the numerical side, generalized functions for constitutive parameters will be used to be able to simulate the single crystal's microscopic deformation behavior observed in experiments. Estimates of the current microscopic stresses and strains are obtained via an efficient and remarkably stable plastic predictor-elastic corrector technique which is incorporated into a nonlinear finite element program. Numerical simulations of uniaxial tests show quantitatively the influence of hydrostatic pressure on current material data. Further numerical studies on the additional constitutive non-Schmid terms elucidate their effect on iron single crystal's macroscopic deformation and localization behavior.     

Inclusion of microscopic rotation of powder particles during compaction in finite element method using Cosserat continuum theory

The effect of microscopic rotation of powder particles in compaction is included in the rigid-plastic finite element method on the basis of the Cosserat continuum theory. In the Cosserat continuum theory, couple stress induced from the microscopic rotation is introduced, and the equilibrium equations of moment for the couple stress are solved simultaneously with those of force. A yield criterion for the Cosserat porous continuum is proposed by taking the effect of the couple stress into consideration, and constitutive equations for the rigid-plastic porous material are derived from the yield criterion on the basis of the associated flow rule. The equilibrium equations of force and moment for the Cosserat continuum are formulated by the use of the Galerkin method. The effect of microscopic rotation of powder particles in plane-strain closed-die compaction is examined. In addition, the calculated result is compared with that for the conventional continuum without the microscopic rotation. © 1998 John Wiley & Sons, Ltd.     

All-optical control of microfluidic components using form birefringence

The reflection and refraction of light at a dielectric interface gives rise to forces due to changes in the photon momentum. At the microscopic level, these forces are sufficient to trap and rotate microscopic objects. Such forces may have a profound impact in the emergent area of microfluidics, where there is the desire to process minimal amounts of analyte. This places stringent criteria on the ability to pump, move and mix small volumes of fluid, which will require the use of micro-components and their controlled actuation. We demonstrate the modelling, fabrication and rotation of microgears based on the principle of form birefringence. Using a geometric anisotropy (a one-dimensional photonic crystal etched into the microgear), we can fabricate microgears of known birefringence, which may be readily rotated by manipulating the input polarization in a standard optical trap. This methodology offers a new and powerful mechanism for generating a wide range of microfabricated machines, such as micropumps, that may be driven by purely optical control.