具有重叠衍射峰低对称晶系材料的定量织构分析

本文给出了具有重叠衍射峰的低对称晶系材料织构定量分析的最新细化方法：将熵最大原则直接引入到以极图数据为约束条件的最小二乘方程中，实现了最小极密度差与熵最大两种优化的同步进行，四方晶系材料的纤维织构模拟例子表明：即使在很锐的织构组分时，依据本文的方法也可以从较少数目极图数据获得准确的织构矢量．     

ODF Determination from One Complete Pole Figure

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CONSTRUCTING COMPLETE POLE FIGURE FROM AN INCOMPLETE ONE

An analytical procedure for rapidly and quantitatively constructing complete pole figures ofcubic materials,based on the fundamental equations of the vector method.has been presented.Here.an incompletely measured pole figure can be completed by using its measured data asconstraint conditions.It also allows the derivation of any other pole figures.     

粒子群算法对织构分析改进最大熵法的改进

将粒子群算法(PSO)成功地应用于改进最大熵法(MMEM),使用两张或单张部分极图数据,即可测算出多组具有宏观对称的冷轧纯铜片样品的完整晶粒取向分布(ODF).这一改进保留了原MMEM的特长,用较少的实验数据即可计算出样品的真ODF,而又消除了原法在求解非线性方程组时需要选取特定初解的困难,从而使MMEM更具普适性和实用性.     

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 在探讨了无取向电工钢工业检测{100}面织构的需求和当前所面临的测量不准或测量方法过于繁杂的基础上，尝试了一种{100}面织构简便的定量测算方法。以市场上3种无取向电工钢板为实验材料，测量了{200}不完整极图。把极图中心附近10°范围内极密度分布的累积定义为{100}面织构，推导出了计算钢板{100}面织构的简便方法。其中根据{200}极图的对称性和极图的已知数据近似推导出了极图的未知部分，从而完成了定量计算过程。定量计算结果与实测极图所表现{100}面织构的强弱趋势一致。利用相似的原理也有可能发展出对其它织构简便而准确的定量测算方法。     

Determination of texture and estimation of anisotropie properties of metallic uranium rods by neutron diffraction

Textures of metallic uranium rods were measured by neutron diffraction. From experimentally measured single and composite pole figures, the crystallite orientation distribution function (ODF) was determined by the harmonic method using a computer program developed for the fiber texture with orthorhombic crystal symmetry. The composite pole figures measured at overlapped peak positions of the diffraction pattern were assumed to be a linear combination of several neighboring single pole figures. The calculated results show that the harmonic method based on this conjecture well recovers the experimentally measured composite pole figures. Anisotropie physical properties such as thermal expansion coefficients and elastic constants due to the texture were evaluated by numerically averaging the second and fourth rank tensors with the calculated ODF, respectively.     

含磷深冲钢板的低分辨织构分析与弹性模量预估

本文应用改进最大熵法,对冷轧与退火状态下的含磷深冲板进行了低分辨织构分析,结果表明,由大约３０个根据主织构特征优选监测点数据计算出的部分ＯＤＦ系数与完整ＯＤＦ相应系数基本一致,根据低分辨织构分析结果预估的弹性模量也与实测值符合较好。     

多晶沉积薄膜生长过程中织构演变的模拟研究

将织构组态熵的概念应用于沉积多晶薄膜织构演变的模拟研究,考虑膜沉积过程中晶体表面能各向异性及应变能各向异性的变化,建立了沉积薄膜晶体择优生长的定量模型;模拟了Ａｌ多晶薄膜沉积过程中晶体的生长规律,分析了织构演变的主要微观物理因素。     

用部分极图数据构建完整极图

本文提出的简捷构建完整极图的定量计算法以一张实测部分极图为约束,根据矢量法之基本方程,确定未测部分的极图。并可定量预测其它晶面的极图。整个构建过程快速、准确。本法的实施,不仅简化了X射线衍射实验,且较大幅度地降低了极图测试工作量,提高了织构分析的效率。     

锌金属织构的标准极图计算

纯锌金属或锌基合金在加工过程中通常形成织构并引起材料的各向异性,获得织构信息对金属材料加工与应用十分重要.利用锌单晶的晶体结构数据、吴氏网、极图与织构的定义建立了纯锌金属任意织构的标准极图的计算方法.绘制了金属锌常见织构的标准极图,为纯锌金属或锌基合金的织构表征标准化和智能化提供了理论支撑.     

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 通常晶粒较大的样品无法采用常规X-ray衍射方法进行织构测试分析。针对粗晶薄带材样品,利用多片样品的侧面构造一个测试表面,从该组合面测得不完全极图并通过ODF计算和ODF转换计算的方法得到样品的晶粒取向信息,结果表明这种方法可以较好地解决粗晶薄带材样品的织构测试问题。     

粒子群优化在最大熵法定量织构分析中的应用

在最大熵法的基础上,采用带有惯性权重的粒子群算法(PSO),测算了多组具有宏观对称的深冲钢板(IF钢)和冷轧纯铜片样品的完整晶粒取向分布,与用阻尼Newton法计算的结果一致,均得到了满意的结果.在测算中无需任何假设,且样品的成分、织构类型及分布状况对计算结果均无影响.     

Efficient and accurate measurement of very sharp crystallographic textures: A new measurement strategy

A new measurement strategy is introduced to determine very pronounced crystallographic textures of polycrystalline materials most accurately and efficiently. It features optimized adaptively refined successive X-ray pole figure measurements. To optimize both the total experimental time as well as the angular resolution, and thus the accuracy of pole figure measurements, traveling salesman problems on the hemisphere of poles have to be resolved. The corresponding algorithm is encoded and implemented as part of the software controlling the texture goniometer. The procedure was applied to pole figure measurements of a NiW alloy with extremely sharp Cube texture. The results are presented and compared to conventional measurement strategies.     

基于Grouplet熵与关联向量机的断口图像识别方法研究

Grouplet变换是通过Haar变换实现的一种二维图像多尺度分析技术,拥有根据图像的纹理结构自适应改变基的能力,从而具有较好的稀疏性。与小波变换相比,Grouplet变换在针对纹理复杂的金属断口图像的识别方面具有更优越的性能;将Grouplet变换与关联向量机结合,采用Grouplet熵作为特征,关联向量机作为识别器,提出了一种新的基于Grouplet熵-RVM的航空构件断口图像识别方法。试验表明:该方法结合了Grouplet变换以及关联向量机的优势,在针对222张断口图像的训练与识别中,识别率达到了85.58%,相比Grouplet熵-SVM方法识别速率提高了5倍。     

VMD复合熵值法在齿轮故障诊断中的应用

针对齿轮实际工况复杂、故障特征难以提取的问题,提出一种基于变分模态分解(Variational Mode Decomposition,VMD)复合熵值法的故障诊断方法.首先,采用VMD方法对不同工况下齿轮振动信号进行分解,并对分解过程中关键参数的选择进行了研究;其次,根据频域互相关系数准则筛选出可有效表征齿轮状态特征的...     

Orientation changes of aluminium single crystals in ultra-precision diamond turning

In this paper, the effects of cutting speed on the variation of surface texture and lattice rotation of diamond-turned surfaces were investigated. The {1 1 1} pole figures were determined at various locations by the X-ray diffraction method. The local lattice rotation at various locations on a machined groove by the electron back-scatter diffraction (EBSD) method was also obtained. A simulation of the orientation change was performed and the theoretical prediction was compared with the experimental results.     

立方系完整ODF测算的改进

本文通过对具有宏观统计对称立方晶系材料用最大熵法测算完整ODF的研究,提出了适于微计算机用的测算方法,并在PANAFACOM—U1200机上建立了相应的软件系统。作者用冷轧磷钢板材的织构对方法(如系统)进行了校验,结果表明,该法是可靠、实用的     

Quantifying the recrystallization texture of tantalum

The utilization of crystallographic texture is gaining acceptance as a commercially viable tool for characterizing the attributes and confirming the quality of engineering materials. Traditionally, x-ray diffraction (XRD) involving the measurement and subsequent analysis of normal-orientation pole figures is used to determine the preferred orientation in sheet metals. Unfortunately, most XRD techniques are incapable of providing quantifying texture information of wrought tantalum. This is because integrative texture measurement methods cannot detect the presence of texture gradients and bands known to be detrimental to the performance of tantalum for select applications. Instead, discrete orientation measurement techniques such as electron backscatter diffraction are required to resolve the microtexture of tantalum. Inverse pole figure maps generated using orientation imaging microscopy have been used to gain qualitative insight into the texture character of wrought tantalum. Recently, a numerical means for quantifying the texture uniformity of tantalum (as well as other materials) from discrete orientation data has been devised and demonstrated.     

Effect of rolling temperature on microstructure and texture of twin roll cast ZK60 magnesium alloy

Twin roll cast ZK60 alloy strip/sheet with final thickness of 0.5 mm was prepared,and effect of rolling temperature on microstructure and texture development was investigated using OM and XRD technique,microstructure and texture were measured on specimens subjected to rolling experiment at different rolling temperature,and macrotexture was also evaluated by X-ray diffraction method.In addition,the(1 010)and(0002) pole figures were measured,and the tensile test was performed to reveal the influence of rolling temperature on mechanical properties.The results show that the microstructure of ZK60 alloy sheet consisted of fibrous structure with elongated grains,and shear bands along the rolling direction after warm rolling.Dynamic recrystallization could be found during the warm rolling process at rolling temperature 350 °C and above.And many fine recrystallized grain could be observed in the shear bands area.It is a little difficult to see the recrystallized grain in the sheet warm rolled at 300 °C because of higher density of shear bands.The warm rolled ZK60 alloy sheet exhibited strong(0002) pole texture,the intensity of(0002) pole figure decreases with the increasing of rolling temperature and the basal pole tilted slightly to the transverse direction after warm rolling.