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材料的织构导致其性能的各向异性。例如取向硅钢要求有高斯织构,这样高压变压器漏磁最小,能量损失最低。纯钛金属材料及其合金应用十分广泛,在常温下是六方晶体,其织构表现形式有别于立方晶体。在本期刊载的论文“工业纯钛金属织构标准极图的计算及分析”中,昆明理工大学材料科学与工程学院陈亮维等给出了纯钛任意织构对任意投影晶面理论极图的绘制方法,并提供了纯钛常见织构的参考极图。这为钛材研制与生产中出现的织构测试提供了分析标准,也为其他六方金属材料如镁、锌金属等材料的织构测试提供了极图分析参考。     

大角度ECAP变形模具制备纯钛的变形织构演化模拟

为了研究等径弯曲通道变形(ECAP)对纯钛变形织构的影响,本研究采用135°模具在室温条件下以C方式对纯钛实施2道次ECAP变形,然后利用X射线衍射(XRD)仪检测了原始纯钛以及ECAP变形后纯钛的织构,并与VPSC自洽理论模型计算的ECAP变形织构进行对比分析。结果表明:原始纯钛组织为等轴状,晶界清晰,其{0002}晶面极图的最大极密度为2.6,且主要为P_1织构,易发生柱面滑移,同时压缩孪生系处于易激活状态。而经1道次ECAP变形后的织构转变为P织构,同时出现C_2织构。经过2道次ECAP变形后,P织构消失,只存在C_2织构。VPSC自洽理论模型计算织构与实验织构大致相同,且2道次ECAP变形之后的纯钛试样均易发生基面滑移、拉伸孪生系更易被激活。     

镁合金AZ80A搅拌摩擦焊焊核区组织金属学演变

采用取像显微分析技术分析了变形镁合金AZ80A搅拌摩擦焊焊核区塑性条带间的金属学演变过程.结果表明:搅拌摩擦焊搭接头焊核区晶粒尺寸、极图、反极图以及晶粒的取向差均呈周期性的变化,组织结构呈条带分布,基体内部经历了周期性的动态再结晶过程.     

高强TA18钛管数控弯曲织构演变数值模拟

目的获得高强TA18钛管数控弯曲过程的织构演变规律。方法基于高强TA18钛管数控弯曲三维弹塑性显式有限元模型以及耦合粘塑性自洽晶体塑性模型(VPSC),获得钛管数控弯曲过程中的织构演变规律,通过单向拉伸、压缩和数控弯曲实验与EBSD分析验证了织构演变预测的可靠性。结果高强TA18钛管数控弯曲过程中,弯曲角度为0°~90°时,弯曲后管材内外侧均形成径向织构与轴向织构。结论高强TA18钛管的初始织构为近径向织构,在数控弯曲过程中,随弯曲角度增大,管材内侧轴向织构逐渐增多,径向织构先减小后增大;管材外侧的周向织构与轴向织构都逐渐增加;实验对比分析表明,预测的织构变化趋势和实验结果基本一致。     

加工图在钛合金中的应用

简要介绍了加工图在钛合金中的应用,主要介绍了加工图的基本原理,分别以几种典型的α钛、近α钛合金、α β钛合金及β钛合金为例介绍了钛合金加工图的特点和加工图在研究合金元素、微观组织对钛合金热加工特性影响方面的应用,总结了优化这几种合金加工工艺的条件,给出了钛合金加工图的一般规律.     

纯钛板的塑性变形与冲压成形性

钛加工材的需求正在世界范围内迅速增加,与此相适应,冲压成形制品(移动电话、电脑外壳等)的用途也在不断扩展.因此,进行与塑性变形行为相关的纯钛的冲压成形性、塑性变形模式和织构的研究很有必要.     

搅拌摩擦加工细晶TA2工业纯钛晶粒长大规律

TA2工业纯钛经过转速180 r/min、行进速度25 mm/min搅拌摩擦加工后发生剧烈塑性变形,获得晶粒尺寸均匀(平均晶粒尺寸为2μm)的细晶组织。在500～600℃对搅拌摩擦加工细晶TA2工业纯钛进行不同时间的退火处理,利用场发射扫描电子显微镜进行组织观察及织构表征,计算晶粒生长指数和激活能,并建立数学模型,系统研究搅拌摩擦加工细晶TA2工业纯钛晶粒长大行为。研究结果表明,搅拌摩擦加工细晶TA2工业纯钛晶粒长大过程中织构具有稳定性,退火处理后晶粒c轴平行于加工方向。当退火温度为550℃时,部分晶粒优先长大,600℃受热下,晶粒快速长大。在500～600℃内,搅拌摩擦加工细晶TA2工业纯钛晶粒的生长指数为3,生长激活能为328. 5 kJ/mol。研究表明,通过搅拌摩擦加工获得的细晶组织具有较好的晶粒稳定性。     

双轴拉伸Bopp薄膜的织构研究

采用双轴拉伸制取α-聚丙烯薄膜即(Bopp膜)。利用极图测试、ODF三维取向分布函数计算和回算极图方法，研究了Bopp晶态膜的择优取向特征。分析结果表明，双轴拉伸Bopp晶态膜具有高度择优取向，主要的织构组分为C轴([001]轴)集中沿拉伸方向(M向)分布，沿膜面分别为(010)，(110)和(130)晶面。即经双轴拉伸的Bopp晶态膜不再是简单的单轴取向状态，呈现类似于金属薄膜的双轴织构特征。     

氮化铝薄膜织构的极图法研究

在X射线衍射结果的基础上,采用极图法研究了AIN薄膜以(DO2)和(100)面的取向分布,发现在一定条件下制备的AIN(002)有很强的织构,并通过极图法来确定X射线衍射所无法确定的AIN(100)面择优取向薄膜中各晶粒c轴间的关系.     

单向轧制70/30黄铜的形变织构及形成模型

对70/30黄铜进行不同形变量的单向轧制,用三维取向分布函数分析这种有宏观统计不对称的形变织构。根据单向轧制的受力状态描述其形成模型。结果表明:单向轧制黄铜形变织构的主织构与换向轧制的主织构相同,但其{110}〈112〉中各组分的强度和漫散程度不同,且强点偏移理想位置;有宏观统计不对称织构是由轧件所受的剪力而致,非正常滑移和剪切带的作用对其形成起着关键作用。     

极图在晶体判定和取向分析中的应用

采用极图法并结合金相法分别对定向凝固生长的FeGa和CuAlNi合金进行了晶体判定和取向分析。结果表明：FeGa舍金为多晶体,表层存在六个晶粒,根据极点分布,确定该舍金为四方晶系;CuAlNi为单晶体,确定欧拉角为φ1=150°,φ=20°,φ2=0°,并据此旋转定向,重新切割后测量极图,晶体得到了很好的定向;极图法判定结果与金相检验结果一致。     

The role of grain orientation in microstructure evolution of pure aluminum processed by equal channel angular pressing

A new approach describing the role of crystallographic orientation in the microstructural refinement of commercially pure aluminum during the successive passes of equal channel angular pressing (ECAP) is introduced. The study is based on analysis of X-ray diffraction texture data that is used to calculate the geometrical position of crystallographic slip planes with respect to the shearing plane of the ECAP die. The angular deviations of {111} slip planes from the macroscopic deformation plane for different processing routes were calculated and compared. The microstructure evolution was investigated using electron back-scattered diffraction (EBSD). The grain size and grain boundary character distribution obtained for each processing route are related to the angles between {111} planes and the shearing plane. It was shown that the more effective routes in grain refinement have higher angles between {111} slip planes and the shearing plane.     

二氧化钒薄膜在α-Al2O3衬底上的外延生长及其金属-半导体相变特性研究

利用ＸＲＤ及ＸＲＤ极图技术表征了用激光剥离技术生长的ＶＯ_２薄膜．结果表明：在衬底温度为５００℃,氧气偏压６．６７Ｐａ的条件下,在Ａｌ_２Ｏ_３（１１２０）衬底上能实现ＶＯ_２的二维外延生长．薄膜的结构除了与沉积工艺有关外,还和衬底的取向密切相关．在Ａｌ_２Ｏ_３（１１２０）衬底上,定向生长的（１００）ＶＯ_２在Ｍｉｌｌａｒ指数＜５时,除了［０１０］以外,不存在其他晶格矢量与衬底相匹配,从而不可能实现三维单晶薄膜的外延生长．电学特性的测试结果显示,在温度为６５℃左右,ＶＯ_２薄膜出现相交,薄膜的电阻率变化达４个数量级．     

Texture Characterization of High-Temperature Superconductor Wires

Texture measurements have been made for BSCCO tapes produced by dip coating and by powder-in-tube techniques. The texture of the Bi2212 grains was characterized for both c axis texture using (001) pole figures from 008 reflections and a–b axis texture using (115) pole figures. The critical current densities of these tapes were also measured and correlated with texture parameters obtained from contours of the pole figures. For the tapes with good current transport, the arrangement of grains in a crystallographic sense was inferred from the pole figures and was found to be consistent with a model based on global alignment of the c axes and the presence of colonies of grains differing mostly in c axis twist.     

Texture development in two-pass ECAE-processed beryllium

Texture development and substructure evolution are described for pure beryllium given two-pass equal channel angular extrusion (ECAE) processing following routes A and C. These routes impose different strain paths between the first and second passes—the former cross-shearing and the latter reversal. Polycrystal calculations that are in good agreement with the texture measurements suggest that basal slip and, secondly, prismatic slip are operative in both passes of both routes. Multi scale polycrystal modeling is shown to effectively predict texture evolution to strains of two caused by both ECAE processing routes. Shear-like deformation textures observed in the second pass of route C are explained by differences in deformation characteristics between the first and second passes.     

高温超导材料织构的定量分析方法

针对高温雪导材料Ｘ射线衍射（ＸＲＤ）谱上衍射峰大量重叠及明显宽化的现象，使用位敏探测器及织构定量分析的改进最大熵法，准确地进行高Ｔｃ材料织构的定量分析。实验指出：使用上述方法的织构定量分析软件，可从大量重叠极图获得准确的织构信息；使用带有位敏探测器的Ｘ射线射仪，可以提高重叠极图测量的准确度，减少复杂材料（低晶体对称具有重叠衍射峰或复相材料）织构定量分析难度．     

Effect of Bi deficiency on grain alignment of BiPb-2223 thin film fabricated using rf sputtering process and on critical current density properties

Abstract

In the present study, thin films prepared as a function of the Bi concentration in the BiPbSrCaCuO system were synthesised. Thin films were fabricated using radio frequency sputtering method. Crystal structure of the films fabricated was determined from X-ray diffraction measurements. The crystal orientation was analysed by X-ray pole figure and in-plane alignment. Both X-ray diffraction and pole figure analysis revealed that crystallinity in the films decreased significantly with decreasing Bi concentration in the system. A systematic decrease in the superconducting transition temperature and hole concentration per CuO plane was obtained with decreasing Bi concentration. The J_c values of the films were calculated using Bean formula. It exhibits a significant dependence on the magnetic field and temperature. It was found that J_c decreased sharply with increasing applied magnetic field. The highest J_c value was found to be 1·06×10⁶ A cm^?2 at 10 K, which corresponded to the best flux pinning among the films fabricated.     

Texture effects under tension and torsion loading conditions in titanium alloys

The paper derives from a major research programme on texture evolution and characterisation in the titanium alloys Ti-6Al-4V and Ti550. The present publication focuses on the mechanical characterisation of the texture in rolled plate. It focuses specifically on monotonic strengths and strain control fatigue under tension and torsion loading. Dependencies of fatigue performance on specimen orientation are interpreted through EBSD evaluation of basal and prism plane intensities within the present materials. The cyclic deformation and mechanisms of failure are related to the relative magnitude of tensile and shear stress components in the tension and torsion loading modes. Stress relaxation is shown to play an important part in these processes. Its relationship to available slip systems is discussed     

Evolution of texture during equal channel angular extrusion of commercially pure aluminum: Experiments and simulations

The evolution of crystallographic texture has been comprehensively studied for commercially pure Al as a function of amount of ECAE deformation for the three major routes of ECAE processing. It has been observed that processing through different routes leads to different type of texture, in both qualitative as well as quantitative sense. The results have been analyzed on the basis of existing concepts on ECAE deformation and simulations have been carried out using the simple shear model of ECAE implemented into the Viscoplastic Self Consistent model of polycrystal plasticity. The simulations revealed that non-octahedral slip is needed to reproduce the experimental texture development.     

The effect of different forms of strain energy functions in hyperelasticity‐based crystal plasticity models on texture evolution and mechanical response of face‐centered cubic crystals

Micro‐mechanical and macro‐mechanical behavior of face‐centered cubic (FCC) crystals is investigated by using different forms of strain energy functions in hyperelastic material models in crystal plasticity finite element framework. A quadratic strain energy function with anisotropic elastic constants, a polyconvex strain energy function with invariants associated with the cubic symmetry, and a strain energy function from an inter‐atomic potential are considered in hyperelastic material models to describe the elastic deformation of FCC crystals. In our numerical experiments, the trajectories of {111} poles in the pole figure and the accumulated plastic slips of FCC coppers under uniaxial tension and simple shear depend on the choice of strain energy functions when the slip resistance of the slip systems is high. The ability of strain energy functions in this study to represent elastic lattice distortions in crystals varies with the amount of elastic deformation and the shape of deformed lattice. However, numerical results show that the change of macroscopic mechanical behavior of FCC coppers is not significant for the choice of strain energy functions, compared with the change of crystallographic texture evolution. Copyright © 2014 John Wiley & Sons, Ltd.