偏析法制备高纯电子铝箔的再结晶织构演变

本工作基于偏析法高纯铝制备的高压电子铝箔,用电子背散射衍射(EBSD)和X射线衍射(XRD)方法研究其在退火过程中的再结晶织构演化,并建立元胞自动机(Cellular automata, CA)模型从能量角度解释不同再结晶机制。实验和模拟结果表明,分级退火时,在低温段变形基体中S型取向({123}〈634〉)和Cu型取向({112}〈111〉)的晶粒通过连续再结晶获得长大优势,立方取向({001}〈100〉)晶粒的形核受到抑制,在后续高温段S型取向和Cu型取向晶粒迅速长大并形成了以S型和Cu型织构为主的再结晶织构;直接高温退火时立方取向晶粒优先形核、长大从而形成强立方织构;CA模型表明两种不同退火条件下的能量差异是造成不同再结晶织构的主要原因。     

加工率对Ni5W合金基带立方织构的影响

以镍粉和钨粉为起始原料,采用粉末冶金的方法形成Ni5W预合金锭,采用真空电弧炉去除杂质,实现均匀化。结合热轧、冷轧和再结晶热处理等工艺制备了厚度为80μm的Ni5W合金基带。讨论了道次加工率、总加工率对Ni5W合金基带轧制织构演变的影响。结果表明,较小的道次加工率和较大的总加工率有利于基带再结晶热处理后立方织构百分含量的提高,道次加工率对立方织构质量的影响小于总加工率。以5%的道次加工率和98%的总加工率进行冷轧后,获得了具有较高含量的S型织构和Copper型织构的基带。     

中间退火对高纯铝箔立方织构的影响

采用晶体取向分布函数（ODF）研究和分析了中间退火对高纯铝箔立方织构的影响。研究结果表明：中间退火对高纯铝箔冷轧形变织构影响不大,但对成品退火箔材中立方织构和R织构含量产生重要影响,在300C/2h中间退火条件下,成品箔材中再结晶立方织构物取向密度最大,R织构含量较小。     

退火时间对单向异步轧制70—30黄铜再结晶织构的影响

借助三维取向分布函数探讨了退火时间对单向异步轧制７０－３０黄铜再结晶结构及其宏观统计不对称性的影响,结果表明,各层再结晶织构存在明显的宏观统计不对称性,是由形变织构的不对称所致;随着退火时间的不断延长,宏观统计不对称性逐渐增强,待再结晶结束后趋于稳定。     

高压阳极电容铝箔生产工艺对立方织构的影响

综合分析了高压阳极电容铝箔生产工艺对立方织构的影响,包括化学成分、热轧,冷轧及热处理工艺等,力求最大程度地增加铝箔中立方织构的含量,以达到提高铝电解电容器比电容和组织均匀化的目的。     

用于涂层导体的Ag/立方织构Cu复合基带的制备

通过二次冷轧铜棒并850℃恒温热处理,制备出具有较强立方织构的Cu基带。以硝酸银、亚硫酸钠和硫代硫酸钠为主要原料配制镀银液,在立方织构Cu基带上制备出具有较强Ag(200)择优取向的银镀层。在600℃恒温热处理30min后Ag膜仍具有(200)择优取向,而830℃热处理后,Ag会扩散到Cu基底中,重复镀银、热处理5次后,Ag膜具有(200)的择优取向并少量面内织构,所得Ag/立方织构Cu复合带材可作为第二代高温超导带材YBCO涂层导体的金属基底。     

立方织构Ni-Cr-Mo-W合金薄带及其性能

为了得到高份额立方织构金属基带,同时兼顾居里温度和屈服强度的要求,设计了Ni-7.8%Cr-1.1%Mo-1.6%W(原子分数)合金。采用冷坩埚悬浮熔炼技术冶炼合金铸锭,铸锭经过锻造、热轧、冷轧和再结晶退火,最终得到厚度为100μm的合金薄带。采用电子背散射衍射(EBSD)技术对合金薄带再结晶织构进行了表征,并研究了其磁性能及力学性能。结果表明:经大变形量冷轧和优化的两步法退火后Ni-7.8%Cr-1.1%Mo-1.6%W合金薄带立方织构份额为93.4%,小角晶界体积分数为84.5%;合金薄带的居里温度为25K,远低于77K;合金薄带室温下的屈服强度为182 MPa,与Ni-5%W合金相当,且抗拉性能十分优异。     

拉深中织构系数对立方晶粒正交板材制耳的影响

板材在冲深过程中由于材料本身的各向异性而引起制耳,这种情况使得材料加工中多一道工序,而且造成材料的浪费,增加成品的造价.引入取向分布函数和织构系数,说明正交板材的各向异性仅与织构系数c004、c204、c404有关,建立正交板材冲深过程中相对径向应变与织构系数的关系式,定量说明制耳与织构间的关系.计算了几种典型织构的相对径向应变,并通过调整各织构组分的比例,达到最小制耳的比例.     

Fe3Si基合金的织构研究

采用两次温轧工艺制备出Ｆｅ３Ｓｉ基合金薄板,分别经过去应力退 完全再结晶退火后进行织构研究。结果表明,首次发现Ｆｅ３Ｓｉ基合金轧制后存在单一组分的「１１０」「１１０」形变织构。基本上不存在再结晶织构,即有序的Ｆｅ３Ｓｉ金属间化合物存在着再结晶织构弱化现象。     

3104铝合金再结晶织构的研究

应用取向分布函数(ODF)研究和分析了3104铝合金经不同工艺退火后的再结晶织构.结果表明:3104铝合金,形变织构由C{112}〈111〉,B{110}〈112〉,S{123}〈634〉织构组分组成;退火温度和保温时间对3104铝合金再结晶织构有重要影响,在低温短时退火时立方织构取向密度较弱,但随温度升高和保温时间的延长,立方织构取向密度逐渐增加,在经350℃60min,400℃60min和450℃15min等温退火后,再结晶基本完成,立方织构取向密度在400℃保温60min退火时达到最大,约为10级,但仍保留有少量冷轧织构;随着退火温度的升高,第二相粒子Al6(Fe,Mn)和Al(Fe,Mn)Si在再结晶过程中起到了粒子促进形核作用(PSN).     

GH4169合金楔横轧加工过程中动态再结晶及织构演变

为研究GH4169合金楔横轧加工过程中动态再结晶及织构演变规律,采用金相显微镜(OM)和电子背散射衍射(EBSD)对30%,50%两种断面收缩率下GH4169合金楔横轧件表层与心部的微观组织、晶体取向及织构进行分析。结果表明:GH4169合金楔横轧加工过程中,随着动态再结晶的发生,晶体取向逐渐变得随机化分布;轧制表层大角度晶界数量较轧件心部多,轧件表层织构强度变化不大,心部织构强度明显增强;经过楔横轧变形后织构发生转动,原始态织构类型为{001}〈110〉,{111}〈110〉,{111}〈011〉,轧制后主要织构类型为{001}〈010〉,{112}〈110〉,{110}〈111〉,{110}〈112〉;GH4169合金楔横轧件动态再结晶及织构演变规律是由楔横轧特殊变形特点决定的。     

Dynamic recrystallization behavior and microstructural evolution of Mg alloy AZ31 through high-speed rolling

High-speed rolling (HSR) is known to improve the workability of Mg alloys significantly, which makes it possible to impose a large reduction in a single pass without fracture. In the present study, dynamic recrystallization (DRX) behavior and microstructural and textural variations of Mg alloy AZ31 during a HSR process were investigated by conducting rolling with different imposed reductions in the range of 20%–80% at a high rolling speed of 470 m/min and 400 °C. High-strain-rate deformation during HSR suppresses dislocation slips but promotes twinning, which results in the formation of numerous twins of several types, i.e., {10–12} extension twins, {10–11} and {10–13} contraction twins, and {10–11}–{10–12} double twins. After twinning, high strain energy is accumulated in twin bands because their crystallographic orientations are favorable for basal slips, leading to subsequent DRX at the twin bands. Accordingly, twinning activation and twinning-induced DRX behavior play crucial roles in accommodating plastic deformation during HSR and in varying microstructure and texture of the high-speed-rolled (HSRed) sheets. Area fraction of fine DRXed grains formed at the twin bands increases with increasing rolling reduction, which is attributed to the combined effects of increased strain, strain rate, and deformation temperature and a decreased critical strain for DRX. Size, internal strain, and texture intensity of the DRXed grains are smaller than those of unDRXed grains. Therefore, as rolling reduction increases, average grain size, stored internal energy, microstructural inhomogeneity, and basal texture intensity of the HSRed sheets gradually decrease owing to an increase in the area fraction of the DRXed grains.     

Effects of initial texture on deformation behavior during cold rolling and static recrystallization during subsequent annealing of AZ31 alloy

This study demonstrates that the initial texture of Mg alloy significantly affects the microstructure developed during cold rolling and the recrystallization behavior during subsequent annealing. In a sample with a texture oriented toward the normal direction(ND sample), thick and large-sized shear bands are intensively formed during cold rolling and the deformation is strongly localized along these bands. In contrast,in a sample with a texture oriented toward the transverse direction(TD sample), many {10-12} twins are formed at the early stage of cold rolling, and then, numerous small-sized shear bands are formed in these twins. Results of nanoindentation tests reveal that the cold-rolled ND sample has internal strain energy that is substantially concentrated along the shear bands, whereas the cold-rolled TD sample has a large amount of internal strain energy that is homogeneously distributed throughout the material;this latter behavior is strongly related to the extensive {10-12} twinning and the resultant microstructural variations in the TD sample. During subsequent annealing, recrystallization occurs locally along the shear bands in the ND sample, which leads to the formation of a bimodal grain structure comprising fine recrystallized grains and coarse unrecrystallized grains. In contrast, during subsequent annealing of the TD sample, static recrystallization occurs homogeneously throughout the material, which results in the formation of a uniform grain structure that mostly comprises equiaxed recrystallized grains.     

Effect of initial texture on dynamic recrystallization of AZ31 Mg alloy during hot rolling

Wedge-shaped AZ31 plates with two kinds of initial textures were rolled at 573 K to investigate the effect of initial texture on dynamic recrystallization (DRX). The results indicated that the initiation and nucleation of DRX were closely related to the initial texture. The initiation and completion of DRX in the TD-plate were significantly retarded compared with that in the ND-plate. Twin related DRX nucleation was mainly observed in the ND-plate samples; while gain boundary related DRX nucleation was mainly observed in the TD-plate samples. The different DRX behavior between the TD- and ND-plates was attributed to the different deformation mechanism occurring before DRX initiation. For the ND-plate, dislocation glide was considered as the main deformation mechanism accompanied with {1 0 −1 1}-{1 0 −1 2} double twin, which led to the increment of a faster increasing stored energy within the grains. And {1 0 −1 1}-{1 0 −1 2} double twin was mainly found to be DRX nucleation site for the ND-plate. For the TD-plate, {1 0 −1 2} extension twin was the dominant deformation mechanism which resulted in a basal texture with the c-axis nearly parallel to ND. The stored energy caused by dislocation motion was relatively small in the TD-plate before a basal texture was formed, which was considered as the main reason of that DRX was retarded in the TD-plate compared with that in the ND-plate. Based on the difference in deformation mechanism and DRX mechanism caused by the different initial texture, the variation in grain size, micro-texture and misorientation angle distribution in the ND and TD plates were discussed.     

Mechanism of cube grain nucleation during recrystallization of deformed commercial purity aluminium

Cube texture is a sharp recrystallization texture component infcc metals like aluminium, copper, etc. It is described by an ideal orientation i.e. (100) (100). The subject of cube texture nucleation i.e. cube grain nucleation, from the deformed state of aluminium and copper is of scientific curiosity with concurrent technological implications. There are essentially two models currently in dispute over the mechanism of cube grain nucleation i.e. the differential stored energy model founded on the hypothesis proposed by Ridha and Hutchinson and the micro-growth selection model of Dugganet al. In this paper, calculations are made on the proposal of Ridha and Hutchinson model and the results are obtained in favour of the differential stored energy model. It is also shown that there is no need for the micro-growth model.     

异步轧制对硅钢极薄带三次再结晶的影响

分别采用同步和异步轧制将成品工业取向硅钢板冷轧到0.045～0.10mm,然后在纯氢气热处理炉中进行三次再结晶高温退火,研究轧制工艺参数对取向硅钢极薄带织构和磁性能的影响,探索异步轧制对硅钢极薄带三次再结晶行为影响机理.结果表明,采用异步轧制取向硅钢极薄带的磁性能优于同步轧制的;硅钢极薄带厚度愈薄,磁性能愈好,三次再结晶发展得越完善.     

Magnetic properties of grain oriented ultra-thin silicon steel sheets processed by conventional rolling and cross shear rolling

A new procedure consisting of the cross shear rolling (CSR) and the subsequent tertiary recrystallization annealing under dry hydrogen atmosphere was developed to produce the grain oriented ultra-thin silicon sheets less than 0.1 mm with high magnetic property performance. For comparison, the conventional rolling (CR) was also used to process the grain oriented ultra-thin silicon steel sheets. The effect of processing parameters on magnetic properties of the grain oriented ultra-thin silicon steel sheets was investigated. With the increase of annealing temperature and holding time, magnetic properties of the sheets processed by both rolling methods reach saturation as the result of the proceeding of the tertiary recrystallization. The thin sheets rolled by CSR did achieve better magnetic properties than those rolled by CR.     

Preparation of self-supporting nickel targets from Ni, Ni and Ni

The investigation of the distribution of the fusion-barrier height by heavy-ion collisions requires thin self-supporting targets. To increase the accuracy of the measurement the thickness and homogeneity has to be known as precisely as possible.We prepared the self-supporting nickel foils out of the isotopes ⁵⁸Ni, ⁶⁰Ni and ⁶¹Ni. The resulting targets were between 75 and 105 μg/cm^² thick. The foils were produced on copper backing by electron-beam gun evaporation and by extracted ion-beam sputtering, both in high vacuum. To obtain self-supporting nickel foils the copper was removed by etching. We will discuss and compare both methods.     

Macro- and micro-modelling of hot rolling of steel coupled by a micro-constitutive relationship

A macro- and micro-combined model has been developed to simulate the static and dynamic recrystallizations of austenite during hot rolling of steel. In addition to the coupled thermal and mechanical phenomena, a micro-constitutive relationship is used to link the macro and micro models. The macro model provides the thermal and deformation information for the micro model. A finishing line with seven stands is studied to verify the model's reliability. The results indicate that static recrystallization plays a more important role than the dynamic part in austenite refinement.     

Dynamic deformation behavior and microstructural evolution during high-speed rolling of Mg alloy having non-basal texture

The dynamic deformation behaviors and resultant microstructural variations during high-speed rolling(HSR) of a Mg alloy with a non-basal texture are investigated. To this end, AZ31 alloy samples in which the basal poles of most grains are predominantly aligned parallel to the transverse direction(TD) are subjected to hot rolling with different reductions at a rolling speed of 470 m/min. The initial grains with a TD texture are favorable for {10–12} twinning under compression along the normal direction(ND); as a result, {10–12} twins are extensively formed in the material during HSR, and this consequently results in a drastic evolution of texture from the TD texture to the ND texture and a reduction in the grain size. After the initial grains are completely twinned by the {10–12} twinning mechanism, {10–11} contraction twins and {10–11}-{10–12} double twins are formed in the {10–12} twinned grains by further deformation.Since the contraction twins and double twins have crystallographic orientations that are favorable for basal slip during HSR, dislocations easily accumulate in these twins and fine recrystallized grains nucleate in the twins to reduce the increased internal strain energy. Until a rolling reduction of 20%, {10–12}twinning is the main mechanism governing the microstructural change during HSR, and subsequently,the microstructural evolution is dominated by the formation of contraction twins and double twins and the dynamic recrystallization in these twins. With an increase in the rolling reduction, the average grain size and internal strain energy of the high-speed-rolled(HSRed) samples decrease and the basal texture evolves from the TD texture to the ND texture more effectively. As a result, the 80% HSRed sample, which is subjected to a large strain at a high strain rate in a single rolling pass, exhibits a fully recrystallized microstructure consisting of equiaxed fine grains and has an ND basal texture without a TD texture component.