超塑性变形Ti-6Al-4V合金中接近重位点阵取向α晶界滑动机制的TEM研究

用 TEM 研究了超塑性变形 Ti_(-6)Al_(-4)V 合金中接近重位点阵取向(near-CSL)的α晶界,发现在部分晶界上晶界位错(GBD:)的衍衬象变得漫散,但仍然保持线状特征;某些 GBD 有局部的分解和束集反应;在α晶界与晶内亚结构的交界处,GBS 通过束集反应形成新的组态;构成晶界坎的各个界面上,GBD 排列的位向各不相同,晶界坎可向晶内发射点阵位错。     

Ti-6Al-4V表面超声滚压制备Al_2O_3膜层的微观组织及性能研究

运用超声滚压处理(USRP)的方法,在Ti-6Al-4V合金表面制得一层Al2O3薄膜。利用SEM、XRD、光学干涉仪及显微硬度计分析了超声滚压处理后试样表面层的微观组织和性能。结果表明:加入Al2O3粉末进行USRP后可以在基体金属表面形成厚度约为7μm的Al2O3膜层,且结合处基体金属存在残余压应力和塑性变形。相对于母材,处理后试样表面粗糙度降低50%,表面硬度提高98%。同时,处理后试样表面层存在残余压应力场,最大压应力值为-687MPa,位于最表层,残余压应力深度为420μm。加入Al2O3粉末的USRP后的试样,既利用表面Al2O3的加入进一步提高其表面硬度,同时保留了USRP的优势。     

ECAP变形对超细晶铜再结晶行为的影响

为研究ECAP变形对超细晶铜再结晶行为的影响,室温条件下对纯铜进行12道次等通道转角挤压(ECAP)变形,分别在100、150、280℃下对不同道次的超细晶铜进行退火处理,分析其硬度及微观组织变化规律.结果表明:经12道次ECAP变形后,铜的晶粒尺寸细化到约250 nm,硬度达146 HV;随着变形道次增加,超细晶铜的热稳定性降低,软化速度加快,在150℃退火时,1道次超细晶铜完成再结晶的时间约为20 h,12道次为0.5 h;12道次ECAP超细晶铜等温退火温度越高,完成再结晶时间越短,150℃完成再结晶时间约为1 200 s,200℃时缩短至600 s,280℃时再结晶仅需50 s;利用Arrhenius公式计算了再结晶激活能,1道次约为1 eV,12道次为0.78 eV,ECAP变形降低了铜的再结晶激活能.     

Ti-4Al-22V合金镀膜处理对其脆性影响的模拟研究

用真空镀膜机和热处理炉对Ti—4Al—22V合金镀膜过程进行模拟热处理，用显微硬度计测量热处理后的合金显微硬度的变化；用测试弯折法测量其塑性；用奥林巴斯显微镜观察合金组织，用JXA—8800R电子探针显微分析仪进行断口试样电子扫描分析和断面成分能谱分析。结果表明：Ti—4Al—22V合金在镀膜处理过程中，容易因加热温度过高而导致脆化，在300℃左右Ti—4Al—22V合金存在一个脆性区间；消除脆性的方法是在450～550℃对Ti—4Al—22V合金进行退火处理，使其发生再结晶和塑性升高；退火处理可以在镀膜前或镀膜后完成。     

常化退火处理对无取向硅钢组织和织构的影响

采用光学显微镜和X射线衍射仪研究了常化退火处理对无取向硅钢热轧板和成品退火板显微组织和织构的影响。结果表明:常化退火处理消除了热轧板中的变形组织,促使变形晶粒完成再结晶;常化退火处理使高斯织构和立方织构易通过再结晶在变形带内形核和长大,可显著降低成品退火板的{111}和{112}不利织构组分的占有率,提高{100}和{110}有利织构组分的占有率,从而有利于提高无取向硅钢成品板的磁性能。     

IF钢再结晶晶粒尺寸、显微织构和晶界特征分布的EBSD研究

对IF钢板的罩式退火工艺和连续退火工艺进行了模拟，并运用电子背散射衍射(EBSD)技术研究了两种退火工艺处理的IF钢板的再结晶晶粒尺寸、显微织构和晶界特征分布及其与二次加工脆性间的关系。试验结果表明，两种退火工艺的IF钢板在再结晶晶粒尺寸、显微织构和晶界特征分布上存在很大的差异，这种差异导致了两种退火工艺的实验钢板在深冲性能和韧脆转变温度上的差异。     

Ti-6Al-4V合金包覆叠轧薄板的轧制工艺对力学性能的影响

主要研究了包覆叠轧加工及热处理工艺对Ti-6Al-4V合金室温拉伸及疲劳性能的影响规律,用金相显微镜和扫描电镜观察分析了疲劳裂纹的扩展路径及断口形貌.结果表明,在交叉轧制状态下,Ti-6Al-4V合金板材的织构较弱,且该状态下的疲劳性能最好,疲劳裂纹尖端有塑性钝化;而在较低轧制温度和单向轧制状态下,合金板材具有强烈的织构,疲劳裂纹呈快速扩展.     

CGO硅钢初次再结晶组织及织构演变规律

对3%(质量分数)Si CGO硅钢冷轧板进行初次再结晶退火实验,设置不同的退火保温时间,将退火后的样品分别使用OM,TEM及EBSD进行分析,观察其微观组织、位错及织构分布,研究CGO硅钢初次再结晶过程中组织及织构的演变规律。结果表明:随着退火保温时间的延长,回复再结晶的程度增加,当保温时间延长至300s时,再结晶基本完成且呈现等轴晶状态,随着保温时间的延长,组织中位错密度降低。初次再结晶退火保温时间对初次再结晶织构分布有影响:随着保温时间的延长,{111}〈112〉和{110}〈112〉织构含量不断下降,{111}〈110〉织构的含量先减少后增加,立方及旋转立方组分基本保持不变,Goss织构组分逐渐增多。当保温时间较短时,晶粒取向差主要为小角度晶界并存在大量亚晶,随着保温时间的延长,大角度晶界逐渐增多。     

LY12铝合金的再结晶织构及晶界特征分布

利用X射线定量织构分析术和背散射电子衍射花样术,研究了冷轧LY12铝合金的再结晶织构及重位(CSL)晶界的分布.结果表明,高温退火样品的再结晶织构与冷轧样品的织构相似;预回复低温退火具有增强再结晶立方{001}〈100〉织构和降低退火S{123}〈634〉、C{112}〈111〉及B{110}}〈112〉织构组分的作用;高强度的再结晶立方织构和一定强度的S织构共存的样品,∑7重位晶界具有较高的出现频度.     

LY12铝合金的再结晶结构及晶界特征分布

利用Ｘ射线定量织构分析术和背散射电子衍射花样术,研究了冷轧ＬＹ１２铝合金的再结晶织构及重位（ＣＳＬ）晶界的分布。结果表明,高温退火样品的再结晶织构与冷轧样品的织构相似;预回复低温退火具有增强再结晶立方｛０１１｝〈１００〉织构和降低退火Ｓ｛１２３｝〈６３４〉、Ｃ｛１１２｝〈１１１〉及Ｂ｛１１０｝｝〈１１２〉织构组分的作用;高强度的再结晶立方织构和一定强度的Ｓ织构共存的样品,∑７重位晶界具有较高的频度。     

Influences of processing parameters and heat treatment on microstructure and mechanical behavior of Ti-6Al-4V fabricated using selective laser melting

Selective laser melting (SLM) has provided an alternative to the conventional fabrication techniques for Ti-6Al-4V alloy parts because of its flexibility and ease in creating complex features. Therefore, this study investigated the effects of the process parameters and heat treatment on the microstructure and mechanical properties of Ti-6Al-4V fabricated using SLM. The influences of various process parameters on the relative density, tensile properties, impact toughness, and hardness of Ti-6Al-4V alloy parts were studied. By employing parameter optimization, a high-density high-strength Ti-6Al-4V alloy was fabricated by SLM. A relative density of 99.45%, a tensile strength of 1 188 MPa, and an elongation to failure of 9.5% were achieved for the SLM-fabricated Ti-6Al-4V alloy with optimized parameters. The effects of annealing and solution aging heat treatment on the mechanical properties, phase composition, and microstructure of the SLM-fabricated Ti-6Al-4V alloy were also studied. The ductility of the heat-treated Ti-6Al-4V alloy was improved. By applying a heat treatment at 850 ℃ for 2 h, followed by furnace cooling, the elongation to failure and impact toughness were found to be increased from 9.5% to 12.5%, and from 24.13 J/cm² to 47.51 J/cm², respectively.The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-022-00389-y     

基于α''组织设计适于激光立体成形的新型高塑性Ti-4.13Al-9.36V合金

为了提高Ti-6Al-4V合金的加工硬化率和塑性,基于其团簇成分式12[Al-Ti₁₂](AlTi₂)+5[Al-Ti₁₄](V₂Ti)设计成分式为4[Al-Ti₁₂](AlTi₂)+12[Al-Ti₁₄](V₂Ti)的(Ti-4.13Al-9.36V, %)合金,采用激光立体成形工艺制备Ti-4.13Al-9.36V和Ti-6.05Al-3.94V(对比合金),研究了沉积态和固溶温度对其显微组织和力学性能的影响。结果表明,沉积态Ti-4.13Al-9.36V和Ti-6.05Al-3.94V合金的显微组织均由基体外延生长的初生β柱状晶和晶内细小的网篮α板条组成。Ti-6.05Al-3.94V合金的初生β柱状晶的宽度约为770 μm,α板条的宽度约为0.71 μm;而Ti-4.13Al-9.36V合金的初生β柱状晶的宽度显著减小到606 μm,α板条的宽度约为0.48 μm。经920℃固溶-淬火处理后Ti-6.05Al-3.94V样品的显微组织为α'+α相,其室温拉伸屈服强度约为893 MPa,抗拉强度约为1071 MPa,延伸率约为3%。经750℃固溶-淬火处理后Ti-4.13Al-9.36V样品的显微组织为α'+α相,与α'马氏体相比,应力诱发的α'马氏体能显著地提高合金的加工硬化能力,其室温拉伸屈服强度约为383 MPa,抗拉强度约为 989 MPa,延伸率达到了17%。这表明,根据团簇理论模型调控α'+α的显微组织能有效提高激光立体成形Ti合金的加工硬化能力和塑性。     

选区激光熔化工艺参数对Ti-6Al-4V成形质量的影响

选区激光熔化是一种利用高能束选择性熔化金属粉末进而直接制造复杂几何形状产品的增材制造技术。采用选区激光熔化成形Ti-6Al-4V样品,分析影响选区激光熔化成形质量的主要因素,采用体式显微镜、金相显微镜、扫描电子显微镜(SEM)、显微硬度计系统研究了不同工艺参数对Ti-6Al-4V合金选区激光熔化成形样品的表面形貌、致密度、组织、显微硬度的影响规律。研究得出Ti-6Al-4V合金选区激光熔化成形的优选工艺参数为:扫描功率450W,扫描速度2 500mm/s,扫描间距0.07mm,该工艺参数下打印出的样品具有较为优良的成形质量,致密度高达97.8%,显微硬度平均值为446HV。     

Superplastic Forming and Diffusion Bonding for Sandwich Structure of Ti-6Al-4V Alloy

Superplastic forming and diffusion bonding (SPF/DB) is a well-established process for the manufacture of components almost exclusively from Ti-6AI-4V sheet material. The sandwich structure of Ti-6AI-4V alloy is investigated. The effects of the microstructure on the SPF/DB process were discussed. The microstructure at the interfaces and the distribution of thickness were researched.     

TI-6Al-4V合金置氢-除氢组织与力学性能

为研究除氢处理对置氢钛合金组织与性能的影响,对Ti-6Al-4V合金在不同参数条件下进行了置氢与除氢处理,采用光学显微镜分析了置氢-除氢处理过程中Ti-6Al-4V合金微观组织的演化规律,通过室温拉伸试验研究了置氢-除氢处理后Ti-6Al-4V合金的力学性能,探讨了Ti-6Al-4V合金置氢-除氢组织与力学性能之间的相...     

增材制造Ti-6Al-4V合金组织调控研究现状

增材制造技术可实现复杂钛合金零件的快速成形,制造的Ti-6Al-4V合金具有较高的强度以及优异的高温性能,被广泛应用于航空、医疗等各大领域。综述了金属增材制造的典型工艺,分析了Ti-6Al-4V合金的相变特征,总结了选区激光熔化制造Ti-6Al-4V的力学性能和组织调控方法,着重分析了热处理温度、冷却速率、变质处理以及超声冲击等对合金组织的影响;展望了增材制造Ti-6Al-4V合金的主要发展方向。     

Effect of Triple Annealing Treatment on Stress Relaxation of Ti-6Al-4V Alloy

The effect of triple annealing on stress relaxation of Ti-6Al-4V alloy as well as the microstructure after stress relaxation werestudied. The results showed that triple annealing treatment enhanced the resistance of stress relaxation performance, andwhen the temperature was rising, this effect became notable. The stress relaxation deformation mechanism is of dislocationcreep at 400℃ and recovery creep at 600℃.     

Annealing behaviour of a nanostructured Cu–45 at.%Ni alloy

The microstructure and crystallographic texture have been investigated in a Cu–45 at.%Ni alloy after heavy rolling and subsequent annealing at different temperatures. Cold-rolling to a von Mises strain of 5.7 produced a sample with an average boundary spacing along the normal direction of ~70 nm and a large fraction of high-angle boundaries (HABs), ~70 %. Annealing of this sample for 1 h at temperatures ≤450 °C causes structural coarsening, during which the fraction of HABs decreases. Annealing at higher temperatures results in pronounced discontinuous recrystallization accompanied by twinning. Large frequencies of twin boundaries contribute to high HAB fractions measured in the as-recrystallized condition. Cube-oriented grains demonstrate a size advantage compared to grains of other orientations, thus creating a strong cube texture in the recrystallized material. Further annealing of the recrystallized microstructure promotes grain growth, which leads to a significant strengthening of the cube texture and to a dramatic loss of HABs. After 1 h of annealing at 1000 °C the fraction of the cube texture reaches 99 % and the HAB fraction is 12 %.     

Mechanical properties of Ti-6Al-4V specimens produced by shaped metal deposition

Abstract

Shaped metal deposition is a novel technique to build near net-shape components layer by layer by tungsten inert gas welding. Especially for complex shapes and small quantities, this technique can significantly lower the production cost of components by reducing the buy-to-fly ratio and lead time for production, diminishing final machining and preventing scrap. Tensile testing of Ti-6Al-4V components fabricated by shaped metal deposition shows that the mechanical properties are competitive to material fabricated by conventional techniques. The ultimate tensile strength is between 936 and 1014 MPa, depending on the orientation and location. Tensile testing vertical to the deposition layers reveals ductility between 14 and 21%, whereas testing parallel to the layers gives a ductility between 6 and 11%. Ultimate tensile strength and ductility are inversely related. Heat treatment within the α+β phase field does not change the mechanical properties, but heat treatment within the β phase field increases the ultimate tensile strength and decreases the ductility. The differences in ultimate tensile strength and ductility can be related to the α lath size and orientation of the elongated, prior β grains. The micro-hardness and Young’s modulus are similar to conventional Ti-6Al-4V with low oxygen content.     

Ti-6Al-4V合金表面超声振动滚压强化研究

采用超声振动滚压加工技术对Ti-6Al-4V合金表面进行处理,探究该项技术对Ti-6Al-4V合金表面质量的影响。通过对该工艺加工前后的Ti-6Al-4V合金进行表面粗糙度参数、XRD图谱、截面微观形貌、表层残余应力及显微硬度的对比分析,结果表明:经该工艺处理后的合金表面各项粗糙度参数皆有明显降低;加工后的合金表面XRD图谱的衍射峰减弱且宽化,衍射角向高角度方向偏移;加工后的合金表层β相组织相较加工前明显细化,且随着深度增加β相组织逐渐增大;在距离表面约50μm位置的残余应力值最大可达到-967 MPa;加工后的合金表面显微硬度可达到421HV,且在0~140μm的深度范围内,显微硬度随着深度的增加逐渐减小至与基体硬度一致。经超声振动滚压加工后的Ti-6Al-4V合金表面质量显著提高,有利于提高其零部件的使用性能。