残余应力测定的基本知识——第四讲X射线应力测定方法(二)

3 定峰方法及其他数据处理 如第四讲所述,X射线应力测定的关键是准确测定衍射角2θ .然而仪器直接测得的是衍射强度I沿接受角2θ的分布曲线,即所谓衍射峰.在计算机控制的步进扫描或使用位敏探测器的情况下,直接测得的是I-2θ坐标系中的一系列"点".     

三维极图及其测定方法

多相材料中各相形状和尺寸的空间分布可能引起Ｘ射线的各向异性吸收，导致其衍射强度取决于试样相对实验坐标体系的三维取向，这种衍射强度的空间三维分布不仅可以提供衍射相的晶体学取向分布，而且能反映各组成的相形状，尺寸几何分布的信息。介绍一种利用普通织构测角器测定三维极图的方法。     

利用Rietveld方法的多相粉末定量分析

利用Ｘ射线步长扫描衍射数据和全图谱（Ｗｈｏｌｅ－ｐａｔｔｅｒｎ）拟合技术（Ｒｉｅｔｖｅｌｄ方法），通过相含量和Ｒｉｅｔｖｅｌｄ修正中标度因子之间存在的简单关系，对包含不同重量的水晶和刚玉粉末的混合物样品进行了相含量的定量分析。求得的结果与原始配比一致，说明这一技术可以有效地用于多相粉末，尤其是衍射图谱严重重叠样品的定量分析研究。     

同步辐射的基本知识——第二讲同步辐射中的衍射术及其应用（四）

4能量色散衍射 4.1波长色散衍射和能量色散衍射 前面讨论的衍射都使用单色X射线的，其透射式的衍射几何实质示于图17a中，处于不同方位的不同d值的晶面在同时刻给出衍射线，探测器作2θ扫描逐步接收各衍射线。如果使用平面探测器或多丝位敏探测器，可同时接收和记录各衍射线，这称为波长色散衍射。各衍射线服从Bragg定律：     

钢板表面镀锌层结构与应变关系研究

应用Ｘ－射线衍射法对不同电镀锌层的结构、表面及缺陷进行了测试和观察。结果表明：日本ＮＫＫ产电镀锌层主要的择优晶面为（１０Ｘ）面（其中Ｘ＝２，３，４），而国产电镀锌层存在（００２）面择优织构。后者存在大量类型不一的缺陷，而前者镀层结构完整。还研究了镀层受力变形后的结构变化，并提出二次粘附成型机理。     

薄膜及镀层织构定量分析

针对薄膜及镀层织构分析的特殊困难（衍射峰特宽、强度测量偶然误差严重、散焦补正困难等），基于熵最大与极密度差最小二乘优化同步进行的原则，提出了织构分析中熵最大处理模式的约束条件，修正了以往约束条件与取向非负性之间的不自生，从而克服了薄膜织构定量分析了困难、模拟研究表明，新方法可以自动补偿测量偶然误及散焦误差，应用实例指出，此法可成功进行实际镀层材料的织定量分析。     

定量确定纤维织构轴密度分布的矢量法

本文将大幅度减少衍射极图测试数目的织构分析矢量法应用于定量确定纤维织构材料的晶粒取向分布;采用蒙特卡罗方法计算系数矩阵σ_(pn)(hkl)。对立方晶系的研究结果表明,由一张极图甚至一张不完整极图即可准确地构建纤维轴密度分布图。     

热致液晶聚酯酰亚胺的WAXD研究

采用Ｘ射线衍射仪、示差扫描热分析仪及偏光显微镜对热致液晶聚酯酰亚胺进行了研究。ＤＳＣ曲线上都有明显的玻璃化转变（Ｔ＿ｇ）及两个熔融峰（Ｔ＿（ｍ１）、Ｔ＿（ｍ２）），表明聚合物具有明显的液晶性；ＷＡＸＤ曲线上在２θ＝２０°左右可观察到较强的衍射峰，在２θ＜１３°的小角范围内也可观察到多个比较尖锐的衍射峰，前者表明分子链横向排列，间距在４．５～５Ａ，后者表明聚合物分子径向采取较完美的层状超分子结构顺序排列，以上结果证实了共聚物是近晶型结构；偏光显微镜下观察到了棒状或小锥状的近晶型液晶的典型织构，进一步支持了ＷＡＸＤ所得结论。     

高聚物结晶度的X射线衍射测定

介绍用Ｘ射线衍射测定高聚物结晶度的方法，以聚丙烯（ＰＰ）样品的测定为例，讨论了分峰法存在的问题及衍射强度的修正，并给出了作者用分峰法测定的聚醚醚酮（ＰＥＥＫ）的结晶度与退火的关系。     

织构C60薄膜的生长及结构特性研究

用气相沉积法在氟金云母单晶衬底上生长高质量的织构Ｃ６０薄膜，Ｘ射线衍射分析表明Ｃ６０薄膜具有高度的（１１１）织构特性，（１１１）晶在平行于氟金云母的（００１）晶面，薄膜在红外区间４０００－１４５０ｃｍ＾－１范围内透过率很 曲线平坦。     

工业纯钛金属织构标准极图的计算及分析

工业纯钛中的金属织构会引起各向异性,获得织构信息及分析其演变规律对钛材加工与应用非常重要.本文利用单晶钛的晶体结构数据、乌氏网、极图与织构的定义,建立了纯钛的织构与特定晶面极图之间的对应关系,理论计算并绘制了纯钛部分织构的标准极图.基于塑性变形时基本滑移面与滑移方向的演变规律,构建了纯钛金属加工方式与织构之间的内在联系,可为六方系纯钛金属或合金的织构演变与表征提供理论基础。     

Recrystallisation mechanism and annealing texture in aluminium-copper alloys

The correlation between the mechanism of recrystallisation and the annealing texture of aluminium-copper alloys was investigated by transmission electron microscopy and selected area diffraction, and pole figure determination by X-rays. Continuous recrystallisation by sub-grain growth leads to preservation of the rolling texture, while recrystallisation by motion of a high-angle boundary produces a cube texture as in pure aluminium. The conditions under which the different modes of recrystallisation occur and the reasons for the formation of the two types of textures are discussed on the basis of microscopic mechanisms.     

Texture mechanism in some fcc-type soft magnetic materials

The authors have studied the mechanism for recrystallization texture in some soft magnetic materials with fcc crystal structure. The alloys used were 77% Ni-14% Fe-5% Cu-4 wt% Mo permalloys. Thin foils selected area electron diffraction (SAD) and X-ray diffraction techniques were employed using a Philips 300 Electron Microscope (EM 300) and an X-ray diffractometer, respectively. Investigations were carried out on deformed, recovered and recrystallized states of the alloys. The various results show that the cold-rolled (deformed) and recovered states of the alloys possess copper-type of rolling texture with {110} 〈112〉 texture as the predominant deformation texture though other minor components such as {112} 〈111〉, {110} 〈001〉 and {123} 〈420〉 textures were detected. No cube texture, {100} 〈001〉 was detected in any of the deformed and recovered materials though the recrystallization texture in these alloys is the cube texture, {100} 〈001〉 which forms over 80% of the annealing texture in these alloys. It is concluded here that the detection of cube texture in the deformed and recovered materials is not a prerequisite for the detection of cube texture in these alloys. The present work is not conclusive about the mechanism for recrystallization texture, but it is proposed here that recrystallization texture, in these alloys is attributed to the growth-oriented mechanism based on the following model. (1) The lattice domains which form the recrystallization texture are present in the cold-rolled matrix. (2) The favoured site for nucleation are the grain boundaries and deformation band boundaries. (3) For the nucleus to be able to grow and form the recrystallization texture it must possess the necessary free energy. (4) Grains must be capable of growth into two or more orientations between which it forms, i.e. the nuclei which form the cube texture should have a [111] pole in common with the matrix in which they grow and a rotation of about 30° around this pole.     

Uniplanar-axial orientation in hot-rolled polymers

The orientations produced by high temperature rolling of polyoxymethylene (126 C) and polytetrafluoroethylene (150 C) and nylon 66 are examined by pole figures. No evidence is found to support the theory of Akahane and Mochizuki that it is the plane of the zig-zag chains that orientates into the rolling plane in nylon 66. The classical rolling texture of Bunn and Garner describes the pole figures except for the (100) pole, which is observed at 28 to the transverse direction; in the texture of Bunn and Garner it should occur at 24 . In hot-rolled polyoxymethylene the texture observed corresponds to a unique orientation of the hexagonal unit cell: (10¯10) planes parallel to the rolling plane and c-axis parallel to rolling direction. The polyoxymethylene texture differs significantly from the pseudo-fibre textures observed in the cold-rolled polymer. The rolling texture of hot-rolled polytetrafluoroethylene is similar to that of hot-rolled polyoxymethylene. These results show the plastic slip system in polyoxymethylene and polytetrafluoroethylene to be (10¯10) [0001].     

Biaxial CdTe/CaF2 films growth on amorphous surface

A continuous and highly biaxially textured CdTe film was grown by metal organic chemical vapor deposition on an amorphous substrate using biaxial CaF₂ nanorods as a buffer layer. The interface between the CdTe film and CaF₂ nanorods and the morphology of the CdTe film were studied by transmission electron microscopy (TEM) and scanning electron microscopy. Both the TEM and X-ray pole figure analysis clearly reveal that the crystalline orientation of the continuous CdTe film followed the {111}<121> biaxial texture of the CaF₂ nanorods. A high density of twin faults was observed in the CdTe film. Furthermore, the near surface texture of the CdTe thin film was investigated by reflection high-energy electron diffraction (RHEED) and RHEED surface pole figure analysis. Twinning was also observed from the RHEED surface pole figure analysis.     

An Approach for Subsurface Rolling Contact Fatigue Damage Assessment of Backup Roll Material

This paper proposed an approach for the subsurface rolling contact fatigue damage assessment of the component operated under rolling contact conditions. The maximum range of orthogonal shear stress was selected as the critical stress controlling subsurface rolling contact fatigue damage. The distribution of the maximum range of orthogonal shear stress combined with the S–N curve of materials tested was used to compute the subsurface rolling contact fatigue damage. The distribution of subsurface rolling contact fatigue damage computed by theoretical model proposed was validated by the statistical analysis result of hardness test on the rolling contact fatigue test samples and distribution of the pole figure’s peak intensity tested by X-ray diffraction method in one of the reference article. The theoretical results agree well with that subsurface rolling contact fatigue damage evaluation characterized by hardness and X-ray diffraction.     

On-line r value determination of deep drawing steel sheet

A potential, rapid and accurate technology to determine r value of deep drawing steel sheets was investigated. The amount of pole figure data which should be measured is reduced drastically because of the pole figure symmetry. The necessary pole figures data can be collected holistically by the X-ray area detectors, after which the volume fraction of the texture components in Gaussian forms is obtained. According to the volume fraction of the texture components, the r value of the steel sheets can be then calculated rapidly and accurately based on the reaction stress deformation model, while some other effecting factors beside texture are also included. The rapid and accurate determination technology overcomes the shortages of current technologies which emphasize either more on velocity or more on accuracy, and can be applied to the on-line r value determination of deep drawing steel sheet.     

An intensity correction for pole figure measurements by grazing incident and grazing exit angle X-ray diffraction

In pole figure measurement by X-ray diffraction, the intensity must be corrected for geometric factors entering into the intensity. For the grazing (often, also called glancing) angle diffraction mode, the irradiated area changes with the grazing angle. A theoretical analysis of this effect was made and compared with measured data from a texture-free silver sample. An intensity correction factor is given as the ratio of the detector slit width and the width of the irradiated sample area as seen from the detector. As an application, the texture of thin copper film was studied.     

On-line r value determination of deep drawing steel sheet

A potential, rapid and accurate technology to determine r value of deep drawing steel sheets was investigated. The amount of pole figure data which should be measured is reduced drastically because of the pole figure symmetry. The necessary pole figures data can be collected holistically by the X-ray area detectors, after which the volume fraction of the texture components in Gaussian forms is obtained. According to the volume fraction of the texture components, the r value of the steel sheets can be then calculated rapidly and accurately based on the reaction stress deformation model, while some other effecting factors beside texture are also included. The rapid and accurate determination technology overcomes the shortages of current technologies which emphasize either more on velocity or more on accuracy, and can be applied to the on-line r value determination of deep drawing steel sheet. __________ Translated from Iron & Steel, 2006, 41(11): 37–41 (in Chinese)