Ta-7.5％W合金箔材冷轧过程中的位错结构演变

本文详细研究了Ta-7.5％W合金中取向为45°立方旋转织构{001}〈110〉方向的晶粒在冷轧变形过程中的位错结构和显微硬度演变规律.结果发现,当冷轧变形10％时,合金中形成了典型的bcc金属冷变形的位错结构,包括位错偶极子、位错反应形成的“剪刀”型位错以及位错碎片亚结构等;随着变形的进一步进行,其中一种晶粒中初期形...     

钽钨合金离子渗氮过程中形成的物相

很多方法可用来硬化钽(固溶强化、塑性变形、晶粒有序化、弥散强化和引入粒状、丝状,晶须和纤维等弥散的强化相)。本文介绍钽及钽钨合金(Ta-10％W)的离子渗氮条件对显微硬度和扩散层相组份的影响。     

50W470硅钢可逆式冷轧过程中的组织织构

利用金相显微镜及XRD衍射仪对可逆冷轧过程中50W470硅钢的组织织构进行分析。结果表明:晶粒长程有序在第3道次被破坏,在金相显微镜下呈现出纤维状的带状组织;经第1道次冷轧变形,晶粒取向首先在α取向线及{001}<110>取向附近汇聚,但从第2道次冷轧变形开始,晶粒取向不断在α、γ取向线及{001}<110>取向附近汇聚,织构的变化主要表现在织构取向密度上。     

钽钨合金动态力学行为及其本构模型研究

本文对两种钽钨合金（Ta-2.5W和Ta-10W,钨的质量分数分别为2.5 %和10 %）的准静态和动态变形行为进行了系统研究。根据准静态压缩实验、霍普金森压杆（SHPB）实验结果,表明两种钽钨合金的屈服应力对加载应变率和钨的含量较为敏感,并拟合得到了两种钽钨合金的JC本构模型。其次,为验证本构模型的合理性,开展了泰勒撞击实验和数值模拟研究,应变率范围为103~104 s-1,数值模拟得到的泰勒杆侧轮廓与撞击端面轮廓与实验吻合较好。最后,为研究钽钨合金变形后的细观特性,对杆件进行了光学显微照片分析。本文的研究方法与结果可为材料本构关系的确定提供借鉴。     

50W470硅钢可逆式冷轧过程中的组织和织构变化

利用金相显微镜及XRD衍射仪对可逆冷轧过程中50W470硅钢的组织织构进行分析。结果表明:晶粒长程有序在第3道次被破坏,在金相显微镜下呈现出纤维状的带状组织;经第1道次冷轧变形,晶粒取向首先在α取向线及{001}110取向附近汇聚,但从第2道次冷轧变形开始,晶粒取向不断在α、γ取向线及{001}110取向附近汇聚,织构的变化主要表现在织构取向密度上。     

钽的加工硬化速率及其显微组织

借助力学性能实验、金相显微镜和透射电镜等手段研究了纯钽的加工硬化速率。研究结果表明:纯钽的宏观加工硬化速率比较低。通过TEM观察,发现变形95%后,纯钽的位错密度都不是很高,存在有位错胞亚结构。其原因可能是因为钽的层错能高,位错容易交滑移,使位错密度降低。根据林位错硬化理论,也可以认为,钽在室温下塑性变形时,滑移系主要为{110}〈111〉,次滑移系的激活比较少,因此穿过主滑移系的林位错密度比较低,位错之间相互作用少,导致钽的加工硬化速率低。     

钽钨合金动态力学行为及其本构模型研究（英文）

对2种钽钨合金(Ta-2.5W和Ta-10W,钨的质量分数分别为2.5%和10%)的准静态和动态变形行为进行了系统研究。根据准静态压缩实验、霍普金森压杆(SHPB)实验结果,表明2种钽钨合金的流动应力对加载应变率和钨的含量较为敏感,并拟合得到了2种钽钨合金的JC本构模型参数。其次,为验证本构模型的合理性,开展了泰勒撞击实验和数值模拟研究,应变率范围为10~3~10~4 s~(-1),数值模拟得到的泰勒杆侧轮廓与撞击端面轮廓与实验吻合较好。最后,为研究钽钨合金变形后的细观特性,对杆件进行了光学显微照片分析。本研究方法与结果可为材料本构关系的确定提供借鉴。     

硅元素对钽丝再结晶行为的影响

采用显微硬度测量、取向分布函数 (ODF)分析及显微组织观察 ,研究了在不同退火温度以及掺硅与未掺硅条件下钽丝的再结晶行为。研究发现 :在 136 0℃退火时掺硅对钽丝的再结晶有阻碍作用 ,晶粒变细 ,丝织构主要由 { 110 }〈0 0 1〉组成 ;当退火温度升高至 15 0 0℃时 ,{ 12 0 }〈0 0 1〉再结晶织构消失 ,在未掺硅钽丝中发现了新的 { 4 41}〈110〉织构组分 ,与初次再结晶织构组分 { 12 0 }〈0 0 1〉之间存在一个近似于 84°〈110〉的转动关系 ,此时 ,掺入硅元素反而促进了再结晶的发展 ,晶粒变得粗大且不均匀。这种现象可以用硅化物的形成与溶解来解释。     

冷轧变形量及退火温度对Ni47Ti44Nb9板材织构和性能的影响

使用X射线衍射技术研究冷轧变形量和退火温度对Ni47Ti44Nb9合金一次冷轧和二次冷轧板织构和性能的影响。结果表明,在冷轧变形量小于35%时,一次冷轧板的织构主要为{111}-110-,与热轧态织构不同,随冷轧变形量的增加,织构取向密度略有提高;二次冷轧板主要织构为{111}-110-,在-110-//RD取向线上从{111}-110-延伸到{110}-110-,二次冷轧使织构取向密度获得较大提高。当二次冷轧板材在高于500℃退火时,其主要织构为{111}-112-再结晶织构,700℃、60 min炉冷样品织构的取向密度明显高于相同制度下水淬样品织构的取向密度。     

退火过程中Fe-6.5％Si冷轧薄板组织及织构的演变

观察分析了Fe-6.5％ Si合金冷轧前后及在不同再结晶退火过程中的组织、织构及有序结构的特点及其演变规律,用以分析织构形成机制及其影响因素.结果表明,间隙溶质原子偏聚于{110}面的概率大于{112}面,明显提高位错在{110}面滑移的临界分切应力;代位溶质原子有可能同步提高{110}和{112}面的临界分切应力,降低这两面的临界分切应力差;因此溶质原子都会导致{112}面更活跃的滑移和更强的{100} <110>冷轧织构.退火过程中{111} <112>取向晶粒易于长入{001}<110>和{112} <110>取向形变晶粒,使{111} <112>再结晶织构增强.冷变形会降低合金的有序化程度;DO3有序化过程的二级相变特点使之在退火加热过程中先于再结晶出现,再结晶之前的回复会促进有序化过程.     

The evolution of dislocation microstructure in electron beam melted Ta-2.5W alloy during cold rolling

The evolution of dislocation microstructure in electron beam melted Ta-2.5W alloy was investigated by transmission electron microscope (TEM). Long straight dislocations and dislocation loops are formed in Ta-2.5W alloy cold-rolled by 5%. A set of long, continuous extending planar boundaries (EPBs) are formed when the reduction reaches 20%. In the early stage of development, EPBs are fragmented, diffused and curved, which are connected by non-crystallographic cells boundaries to maintain their continuity. The straight segments of EPBs are usually parallel with the trace of {110}, and incline at about 25–35° to the rolling direction (RD). Two groups of EPBs are formed in a grain when the reduction is larger than 30%. The dislocations within EPBs tend to rearrange themselves with increasing strain in a sequence, from tangled dislocations, followed by parallel long straight screw dislocations and finally into dislocation nets, which are composed by 1/2 < 111 > and [100] type dislocations. The relaxation process of dislocations and the interaction of dislocations with EPBs make EPBs appear wavy and deviate from the trace of slip planes.     

Effects of grain size on the microstructure and texture of cold-rolled Ta-2.5W alloy

The effect of grain size on the texture and deformation microstructure of cold-rolled Ta-2.5W alloy has been investigated. The alloy with fine grains has higher microhardness than that with coarse grains under the same cold-rolling conditions. Microbands are developed when the cold-rolled reduction reach 20% and the density of microbands increases with increasing reduction. The boundaries of microbands consist of cross dislocation network when cold-rolled by 40%. Meanwhile, mature α and γ fibers are developed in these two alloys. Compared the alloy with coarse grains, the alloy with fine grains has a stronger texture intensity of γ fiber, which is mainly composed of microbands. Meanwhile, the average space between boundaries of microbands is smaller than that in alloy with coarse grains. The effect of subgrain strengthening and texture strengthening in fine-grain alloy is greater than those in coarse-grain alloy.     

锆合金在应变速率1000s~(-1)下动态压缩显微组织的演化规律(英文)

研究锆合金在应变速率1000s-1动态压缩条件下的显微组织演化规律。基于相同应变速率下多次撞击的方法实现锆合金动态压缩下4个不同的应变水平。在不同的应变水平下,应力—应变曲线具有明显的应变硬化效应,几乎观察不到明显的热软化效应。标定的晶粒边界图像表明,在不同的应变水平下,在变形组织内均可观察到大量的小角晶界,同时,小角晶界的数量和密度随着应变的增加而增多。除了在晶粒边界图像中观察到的小角晶界和大角晶界外,在不同的应变水平下还可观察到孪晶界。孪晶界的类型主要包括{10 1 2}、{11 2 1}拉伸孪晶和{11 2 2}压缩孪晶,且大多数孪晶界为{10 1 2}拉伸孪晶。随着应变水平的增加,变形组织中孪晶界的密度变化不明显。基于不同应变水平下变形组织的表征,提出了动态载荷下锆合金变形和演化过程。显微硬度测试表明,撞击试样的硬度随着应变的增加而逐渐增大,这主要与位错塞积引起的应变硬化有关。     

激光熔覆Ta-W合金组织及高温气动烧蚀性能

以纯W粉末为熔覆材料,纯Ta为基底,采用同轴送粉激光熔覆技术在Ta板侧面制备了Ta-W合金涂层。利用扫描电镜(SEM)、能谱(EDS)及显微硬度计对熔覆层的微观组织和显微硬度进行了分析,在直联式自由射流风洞试验台上对涂层的抗高温高速气流烧蚀性能进行了测试。结果表明,熔覆层与基底冶金结合,涂层内部为致密的树枝状Ta-W合金固溶体,大致均匀地分布于Ta中。Ta-W合金涂层平均HV硬度8GPa,为基材的5倍,同时抗烧蚀性能得到了显著提高。     

Texture Evolution in a Ti-Ta-Nb Alloy Processed by Severe Plastic Deformation

Titanium alloys are extensively used in a variety of applications because of their good mechanical properties, high biocompatibility, and corrosion resistance. Recently, ??-type Ti alloys containing Ta and Nb have received much attention because they feature not only high specific strength but also biocorrosion resistance, no allergic problems, and biocompatibility. A Ti-25Ta-25Nb ??-type titanium alloy was subjected to severe plastic deformation (SPD) processing by accumulative roll bonding and investigated with the aim to observe the texture developed during SPD processing. Texture data expressed by pole figures, inverse pole figures, and orientation distribution functions for the (110), (200), and (211) ??-Ti peaks were obtained by XRD investigations. The results showed that it is possible to obtain high-intensity share texture modes ({001}??110??) and well-developed ?? and ??-fibers; the most important fiber is the ??-fiber ({001} $ \left\langle {1\bar{1}0} \right\rangle $ to {114} $ \left\langle {1\bar{1}0} \right\rangle $ to {112} $ \left\langle {1\bar{1}0} \right\rangle $ ). High-intensity texture along certain crystallographic directions represents a way to obtain materials with high anisotropic properties.     

B2结构的铝-镝金属间化合物位错性质的研究

采用截断近似法,研究了B2结构的铝-镝(B2-Al Dy)金属间化合物{110}面的位错性质。结果表明,伯格斯矢量为<110>方向的螺位错、刃位错和混合位错的芯宽度都要比<100>方向窄。它们相应的不稳定层错能存在γus<110>大于γus<001>的关系,可见,不稳定层错能是影响具有B2结构的金属间化合物位错性质的重要因素之一。B2-Al Dy滑移系为<111>{110}的位错,除了位错角为54.7°的位错以外,其他位错角的弹性应变能都要大于失配能,而且在相同周期内看,它们的相位总是相反;位错角为54.7°的位错,失配能比弹性应变能大,而且两者在相同周期内同相位。总体来说,B2-Al Dy的{110}面上<100>、<110>和<111>方向的位错,随着位错角的减小(<111>方向的54.7°的位错角除外),总能量以及相应的应力都依次增大。     

爆炸冲击波强度对16Mn钢焊缝铁素体位错结构和形态的影响

研究了冲击波对１６Ｍｎ钢焊缝铁素体位错结构和形态的影响结果表明，在冲击波塑性作用区，上要表现为螺形位错的增值和缠结，随着冲击波强度的降低，增值和缠结的程度降低；在冲击波的弹－塑性交界区，主要表现为刃型位错的增值和缠结，在弹性作用区同样随冲击波强度降低而降低．位错主要产生于晶界或晶界附近．不同晶面的位错结构和形态不同，｛１１０｝面的位错密度及缠结程度最大．所研究状态下的位错密度和形态不受晶粒尺寸的影响．     

Evolution of deformation microstructures of cold-rolled Ta–2.5W alloy with coarse grains at low to medium strains

Ta–2.5W alloy with coarse grains was cold-rolled to reductions ranging from 5 to 40%. The evolution of the microstructure was investigated by optical microstructure, electron backscatter diffraction (EBSD). A few microbands appear when the reduction reaches 20%. The density of microbands increases with increasing reduction. When the reduction reaches 40%, grains are composed of one or two groups of microbands except the {001}<110 > orientations. Most of the inclination angle between microbands and RD in this condition is 20–35°. As the strain increases, the inclination angle between microbands and RD gets smaller. The habit plane of microbands can be {110} plane. The microbands and matrix usually share a common < 110 > or < 111 >. The mature body-centered cubic rolling texture, including α and γ fibers, is not developed until the reduction reaches 40%. Meanwhile, shear bands appear. New grains can be seen in shear bands and a model is proposed to explain this 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。