Temperature dependence of microstructure and texture in cold drawn aluminum wire

The effect of strain and drawing temperature on the evolution of microstructure and fiber textures of aluminum wires drawn at room temperature and cryogenic temperature was investigated by TEM and EBSD observations. The results show that low angle boundaries frequency increases and high angle boundaries frequency decreases with strain increasing when the strain is low. At high strain, most of grain and dislocation boundaries are parallel to the drawn direction and low angle boundaries frequency decreases and high angle boundaries frequency increases with strain increasing. The decrease of deformation temperature leads to microstructure finer and low angle boundaries frequency increasing. Texture analysis indicates that volume fraction of complex texture component decreases with strain increasing and a mixture of 〈111〉 and 〈100〉 fiber texture forms at high strain. 〈111〉 is stable at low strains but 〈100〉 becomes stable at high strain. The decrease of temperature can enhance the stability of 〈111〉 orientation at high strain.     

Ti-IF钢罩式退火过程中再结晶织构演变规律研究

采用X射线衍射技术(XRD)和电子背散射衍射技术(EBSD),并结合微观组织观察分析了Ti-IF钢罩式退火过程中织构演变规律和{111}再结晶织构形成机制.结果表明:随退火温度的升高,再结晶量逐渐增多,{111}再结晶织构强度亦逐渐增强,同时{100}织构强度逐渐减弱.{111}取向的品粒主要在再结晶过程中形成,依靠吞并其他取向[主要是{100}取向]的晶粒而长大;并且在{111}取向品粒长大过程中,γ纤维织构之间也发生相互转化,主要由{111}<112>织构转变为{111}<110>织构;冷轧IF钢再结晶退火后具有较强的γ纤维织构,主要是"取向形核"和"取向长大"共同作用的结果,其中Σ重位晶界在再结晶γ纤维织构形成过程中起着重要作用.     

退火对Ni-W合金药型罩组织与性能的影响

用电沉积方法制备了含钨1.76%(质量分数)的Ni-W合金药型罩。通过拉伸试验对原始电铸态和热处理后样品的力学性能进行了评价,并利用X射线衍射、透射电子显微镜、俄歇电子能谱等技术对原始电铸态和热处理后样品的微观结构进行了分析。结果表明,通过电铸技术制备的Ni-W合金药型罩材料强度较高,晶粒细小并具有(111)织构。制备的Ni-W合金仍具有面心立方结构,W固溶在Ni的晶格中。Ni-W合金药型罩材料经300℃退火后,晶粒发生异常长大,(111)织构转变为(220)织构。经500℃退火后,由于硫在晶界的偏析,发生沿晶断裂,严重影响了材料的力学性能。     

Microstructural evolution in electroplated Cu thin films

The microstructural evolution of electroplated Cu films (0.89 to 3.0 μm thick) has been studied by texture analysis. Before annealing, the volume fraction of (1 1 1) grains decreases with increasing film thickness, while that of (1 0 0), (1 1 0), and randomly oriented grains increases. Annealing causes a decrease in the 1 1 1 fiber intensity in the thinnest films due to growth of randomly oriented grains and multiple twinning.     

Crystallographic Texture Difference Between Center and Sub-Surface of Thin Cold-Drawn Pearlitic Steel Wires

The texture difference between the center and sub-surface of pearlitic steel wires, which were manufactured by continuous cold drawing, was investigated by orientation distribution function based on electron back-scattered diffraction at different drawing passes. A perfect 〈110〉 fiber texture parallel to drawing direction develops gradually with drawing strain increasing at the wire center, while at the sub-surface, a quasi 〈110〉 fiber texture with the 〈111〉 orientation nearly parallel to the circumferential direction is found. This texture at the sub-surface is softer than the perfect 〈110〉 fiber texture in tension. The reasons for this texture difference and influences on the wire’s mechanical properties are discussed.     

Q235碳素钢应变强化相变过程中铁素体晶粒取向分析

利用Ｘ射线衍射和背散射电子衍射（ＢＳＥＤ）分析了单向热压缩条件下碳素钢Ｑ２３５应变强化相变产生的铁素体及 先共析铁素体在应力作用下的晶粒取向分布特点,结果表明,通过应变强化相变产生的铁素体晶粒取向并非完全随机分布,而有较 强的（１１１）／／ ＮＤ线织构 这明显不同于形变铁素体和部分动态再结晶的铁素体晶粒取向待征,先共析铁素体的相对量与（１００） ／／ＮＤ线织构的强度对应。ＢＳＥＤ局部取向（差）定量分析表明,（１１１）取向既可来自应变强化相变,也可来自形变的先共析 铁素体。虽然先井析铁素体形变后外形为形变长条状,但内部仍存在一定的大角晶界;表明先共析铁素体在大应变下进行了一定程 度的动态再结晶     

典型Fe-Cr-Al及Ni-Cr-(Fe)系电热合金丝的显微组织与织构

选取了两类典型电热合金丝材成品进行了检测,对比分析了合金丝的显微组织及织构,包括Fe-Cr-Al系的国产0Cr25Al5合金与进口0Cr22Al5合金和Ni-Cr-(Fe)系的国产Cr20Ni80合金与Cr20Ni30合金。结果表明:进口Fe-Cr-Al合金的平均晶粒尺寸相对较大,晶粒尺寸分布较为均匀,而织构较弱;国产0Cr25Al5合金的平均晶粒尺寸均匀程度较差,而较粗的样品平均晶粒尺寸较大且织构稍弱,接近于进口Fe-Cr-Al合金,表明较粗的丝材制备形变量较小。Ni-Cr-(Fe)系的合金均表现为不均匀的晶粒组织,而Cr20Ni80合金相较于Cr20Ni30合金的大尺寸晶粒更多;减小合金丝材的直径有细化组织作用,同时还能增强两种Ni-Cr合金丝中均存在的<111>丝织构。     

退火温度对双相纤维复合Cu-12%Ag合金织构的影响

采用强拉拔应变制备了双相纤维复合Cu-12%Ag(质量分数)合金线材,并在不同温度下退火,研究了退火温度对该合金两相中晶体织构强度和分布的影响.随着退火温度升高到400℃,Cu相中(111)织构强度降低而〈100〉强度上升,Ag相中〈111〉强度变化不明显;退火温度高于400℃后,两相中的织构强度均有所增加.在较低的退火温度下,应变形成的Ag相织构稳定性高于Cu相.在退火过程中,相界面迁移,复合组织的聚集、纤维相的球化及等轴晶粒的粗化等仅导致形变织构分量相对强度的变化而形成退火织构,因而退火织构的组成与形变织构的组成相同.     

Relationship between microstructure homogeneity and bonding stability of ultrafine gold wire

Inhomogeneous microtexture evolution during the cold drawing process usually results in lean, sway, or sweep failure. The <111> longitudinal fiber texture has higher stiffness than the <100> texture and its proportion and distribution in the cross-section are critical for the bonding stability of fine gold wire. We investigated the inhomogeneous microtexture evolution of gold wire that was cold drawn through an asymmetric diamond die. In this study, the distributions of the <111> and <100> textures in a 20 μm diameter fine gold wire are the variables and their effects on the bonding stability of the wire were estimated by electron backscattered diffraction (EBSD) and finite element method (FEM) simulations. The use of a focused ion beam apparatus enabled a high quality of band contrast of the EBSD to be achieved in the exact half cross-sectional area of the fine gold wire. The detailed three-dimensional FEM results show that the asymmetric distribution of the textures plays a crucial role in increasing the spatial displacement of the gold bonding wire.     

转速对6082-T6铝合金搅拌摩擦焊焊接接头织构的影响

采用电子背散射衍射技术,借助取向成像分析软件,研究了搅拌头在不同转速下,6082-T6铝合金搅拌摩擦焊焊核区上表面晶粒形貌、晶界特征、织构组分的演化. 结果表明,在搅拌针所引入的剪切应力作用下,焊核区形成(110)[001]高斯织构和(114)[$ 22 {\\bar 1} $]织构,轴肩的顶锻压力使其沿着TD方向旋转一定角度,形成(112)[$ 11 {\\bar 1} $]铜织构,随着搅拌头转速的提高,晶粒沿着TD方向旋转角度增加,进一步形成(100)[011]剪切织构和($ 11 {\\bar 1} $)[112]织构;焊核区晶粒受到搅拌针的挤压而形成[110]丝织构,搅拌头转速从1 200 r/min提高到2 000 r/min时,挤压程度增加,导致[110]丝织构组分显著增多.     

Microstructural development in equal-channel angular pressing using a 60° die

Billets of pure aluminum and an Al–1%Mg–0.2%Sc alloy were successfully processed using equal-channel angular pressing (ECAP) with a die having an internal channel angle of 60°. Careful inspection of the microstructures after ECAP revealed excellent agreement, at both the macroscopic and the microscopic levels, with the theoretical predictions for shearing using a 60° die. The grain sizes introduced with the 60° die were slightly smaller than with a conventional 90° die; thus, the values with these two dies were ∼1.1 and ∼1.2 μm in pure Al and ∼0.30 and ∼0.36 μm in the Al–Mg–Sc alloy, respectively. Tensile testing of the pure aluminum at room temperature revealed similar strengthening after processing using either a 60° or a 90° die. In tests conducted at 673 K, the Al–Mg–Sc alloy processed with the 60° die exhibited significantly higher elongations to failure due primarily to the larger strain imposed with this die. It is shown using orientation imaging microscopy that superplastic flow in the Al–Mg–Sc alloy produces an essentially random texture and a distribution of boundary misorientations that approximates to the theoretical distribution for an array of randomly oriented grains.     

Texture development during grain growth in polycrystals with strong preferred orientation

Texture alterations accompanying grain growth have been simulated by means of a new statistical model which for the first time takes into account the dependence of both the energy and mobility of grain boundaries on their disorientation. Model polycrystals with a single-component texture are assumed to consist of preferably oriented grains A (the main texture component) and randomly oriented grains B. Therefore, there are three types of grain boundaries in these polycrystals: high-angle A–B and B–B boundaries, and A–A boundaries with a smaller disorientation. A novel map showing the effect of both the scatter and intensity of the main texture component on the character of grain growth is obtained. Abnormal grain growth leads eventually to vanishing of the main texture component. However, the main component enhances at the incubation period of abnormal grain growth, especially in the case when the initial distribution of randomly oriented grains is displaced toward small sizes, as in materials with cube texture. The texture evolution during normal grain growth is strongly affected by the initial position of the size distribution of randomly oriented grains. If this distribution is displaced toward small sizes, the main texture component is enhanced. In contrast, normal grain growth results in vanishing of the main component if the initial size distributions of grains A and B are identical. Various texture evolutions observed in the simulations are shown to be a result of an interplay of the consumption and the growth of randomly oriented grains during the growth process.     

等通道球形转角挤压过程中工业纯铝的微观组织演变与力学性能

突破传统ECAP变形全过程通道等截面思路,提出一种耦合剪切应变和正应变于一体的新型等通道球形转角挤压(equal channel angular extrusion with spherical cavity,ECAE-SC)工艺。在自行研制的模具上对工业纯铝进行室温单道次ECAE-SC挤压实验,采用OM、EBSD和TEM等技术手段,研究了ECAE-SC变形过程中工业纯铝微观组织的演变规律,并测试了变形后试样的显微硬度。结果表明,在ECAE-SC工艺剧烈简单剪切变形诱导下,工业纯铝仅需1道次挤压变形即可获得等轴、细小、均匀的超细晶组织,平均晶粒尺寸约为400 nm;工业纯铝室温ECAE-SC变形以位错滑移为主并伴有不完全连续动态再结晶,其微观组织经历了剪切带→位错胞→小角度亚晶→大角度等轴晶粒等动态演化过程。1道次ECAE-SC变形后,工业纯铝组织以{110}001高斯织构为主,同时存在部分{111}112铜型织构;材料显微硬度值大幅提升,由初始289.4 MPa提高到565.3 MPa,增幅高达95.33%,且分布均匀性良好。     

磁场预退火对取向硅钢二次再结晶组织及织构的影响

对二次冷轧后高温退火前3.2%Si取向硅钢在实验室自主设计研发的脉冲磁场预退火管式炉内进行不同温度的预退火处理,通过光学显微镜与XRD对其组织织构进行分析,利用硅钢片磁性能测试系统对高温退火后的试样进行磁性能分析。结果表明,经脉冲磁场预退火处理后,整体上取向硅钢平均晶粒尺寸随预退火温度升高略微减小,晶粒尺寸主要集中在10~25 μm范围内;通过ODF图及{200}极图分析可知,经脉冲磁场预退火后,最强织构随预退火温度的升高从{112}<110>织构变化到{223}<110>织构和{111}<110>织构;随着预退火温度的升高,高温退火后试样的磁性能反而降低。     

Effect of initial textures on texture formation in AA 3004 sheets during continuous confined strip shearing and subsequent annealing

The effect of initial textures on the texture formation during continuous confined strip shearing (CCSS) and subsequent annealing was investigated in AA 3004 sheets. The CCSS tools were designed to provide a constant shear strain of the order of 0.5 per pass while preserving the original sheet shape. During the CCSS deformation, the initial texture disappeared, and shear texture components developed. However, the intensity of the shear texture components did not further develop with an increasing number of CCSS passes. The softer initial sample depicting the cube texture displayed the evolution of {111}//ND fiber orientations. Upon recrystallization annealing, the textures developed during CCSS were randomized through the suppression of oriented nucleation and selected growth which generally dominate the evolution of recrystallization texture in cold rolled aluminum alloy sheets.     

Anisotropy and texture in thin copper films—an elasto-plastic analysis

The role of elastic anisotropy on the stress inhomogeneity and effective behavior of columnar grained textured Cu thin films have been analyzed within a continuum framework. The analysis is based on a three-dimensional model of a film/substrate system. The film exhibits a fiber texture with (111), (001) and randomly oriented grains. Mainly two load cases have been considered. Biaxial loading of a film deposited on a silicon substrate and tensile loading of a film deposited on a polyimide substrate. The stress distributions in the (111) and (001) grains were generally found to be very different when subjected to biaxial loading and quite similar when subjected to tensile loading. When plastic behavior is invoked, a structural hardening effect is observed. The plastic behavior differs significantly between biaxial and tensile cyclic loading respectively. A new orientation dependent hardening law is proposed. This hardening law causes the plastic hardening behavior to be orientation dependent and scale with elastic anisotropy. The newly proposed hardening law is demonstrated on a film with small grain aspect ratio.     

Effects of Zn content and initial grain size on double peak basal textures of Mg-Zn-Al alloys

This study investigates the effects of Zn content on the double peak basal textures of extruded Mg-Zn-Al alloys. Two-step plane strain compression (PSC) tests (PSC at room temperature as a first step and PSC at high temperature as a second step) were conducted under various temperatures (200-340 °C) and initial strain rates (0.0002 s^-1 and 0.04 s^-1) using the extruded ZA11, ZA31 and ZA61 alloys. Additionally, to examine the effects of initial grain size on the double peak basal texture, two-step PSC tests were conducted using annealed ZA61 and cast ZA63 alloys. Tilt angle corresponding to the peak in the double peak basal texture increased with increasing Zn content. This correlation was clearly shown especially at low temperature and high initial strain rate. The tilt angle corresponding to the peak increased with decreasing initial grain size.     

磁场作用下电沉积镍层织构及表面形貌分析

分别在垂直和平行磁场环境下电沉积镍,利用XRD和SEM研究了电流密度、磁场强度、磁场方向、超声强度对镍晶镀层织构,以及磁场强度对镀层表面形貌的影响作用,并对其影响机理进行了分析。结果表明:增大电流密度对(200)晶面取向具有促进作用,随着电流密度的增大,晶面织构由以(111)为主变为以(200)为主;磁场强度增加会促使镀层织构(111)晶面取向增强,平行磁场相较于垂直磁场更有利于晶粒生长;超声作用会使晶粒由择优取向变为随机取向;此外,施加磁场作用后,晶粒尺寸随磁感应强度增加而减小,表面更加均匀。     

Relative orientation of the constituents on the degree of crystallographic coherence in AlN/TiN superlattices

AlN/TiN multilayer thin films with the layer thickness ranging from 1 nm to 50 nm were synthesized at 400 °C using a dual-cathode magnetron sputtering. Two series of samples were prepared under conditions of epitaxially matching orientations and far from the epitaxy to study the possible influence of the relative orientation of the constituents on the formation of coherent structures and hardness enhancement of superlattices. Both XRD and TEM observations showed that in large composition modulation period films each constituent grows under its own growth kinetic, leading to the formation of randomly oriented nanocrystalline layers. Decreasing progressively the layer thickness to beneath ≈ 10 nm favours the alignment of (002) basal plane of h-AlN on (111) plane of c-TiN, and results in development of strong (111) texture, prerequisite for stabilisation of c-AlN and the formation of epitaxially coherent structures. The increase of hardness coincides with the contraction of TiN lattice and transition of structures from a randomly oriented nanocrystalline layers to highly (111) textured superlattices. When the relative orientation of the constituents is far from the epitaxy relation, a partial crystallographic coherence of nanocrystalline domains can be obtained with (200) texture, leading to moderate enhancement of hardness.     

IF钢退火过程中再结晶行为的EBSD表征

借助EBSD等技术研究了从冷轧到退火过程中IF钢中铁素体再结晶晶粒的取向演变。研究结果表明,从冷轧到退火过程中,铁素体晶粒取向向着平行于法向的[111]晶粒演变,而平行于法向的[100]晶粒逐渐消失;在冷轧变形过程中,铁素体晶粒的晶体取向决定着发生滑移变形的难易程度,与[100]晶粒相比,[111]晶粒更易于发生滑移变形,并在晶粒内部积累大量的位错,储存了大量的应变能,在随后的退火过程中,应变能较高的[111]晶粒优先形核并长大,优先发生再结晶,而应变能较低的[100]晶粒的再结晶受到阻碍。随着退火温度的升高,γ织构([111]//ND)明显增强,其织构组分(111)[112]尤为明显。