LF6铝合金的超塑性和扩散连接的组合工艺

研究了ＬＦ６铝合金的超塑性和扩散连接组合工艺，试验结果表明；预先采用变形再结晶的方法细化材料的晶，并有效地去除铝合金的致密氧化膜，即可成功地实现铝合金的ＳＰＦ－ＤＢ组合工艺。利用电子探针从微观观察了扩散连接接头的界面扩散行为，并首次从机理上分析珥金属的超塑性和扩散连接两种工艺之间的内部联系。     

(Cu50Zr50)92Al8非晶合金在过冷液相区的超塑扩散连接

(Cu50Zr50)92Al8非晶合金在过冷液相区表现出优异的超塑性,并且成功的进行了超塑扩散连接(SPF/DB)。根据DSC曲线确定了非晶合金的过冷液相区范围为68℃,并且根据非晶合金在过冷液相区的压缩真实应力-应变曲线,选取了超塑扩散连接实验的连接压力为200MPa,连接温度为470~490℃。XRD图谱显示经过超塑扩散连接后的非晶合金发生了部分晶化,显微硬度提高。将经过超塑扩散连接的样品置于万能拉升机上进行三点弯曲实验至发生断裂,通过对断口形貌的观察分析和界面处的力学分析考察了连接质量。在保持连接压力200MPa不变的情况下,非晶合金获得最好连接效果的工艺参数是:连接温度480℃,连接时间3h。     

Ti2AlNb合金超塑性能及四层立筋结构超塑成形/扩散连接工艺

对Ti-22Al-27Nb合金四层结构件SPF/DB组合工艺进行试验研究,对Ti-22Al-27Nb合金的超塑性能及扩散连接性能进行探究。拉伸实验表明,当变形温度为960℃、应变速率为1×10^?4 s^?1时,材料伸长率达到最大,为230%。对温度、保温时间和扩散压力对Ti-22Al-27Nb合金接头质量的影响进行研究,结果表明Ti-22Al-27Nb合金扩散连接的最佳工艺参数为(960℃,10 MPa,2 h)。根据高温拉伸试验结果,利用有限元模拟软件对中空四层结构件超塑成形过程进行模拟。通过SPF/DB组合工艺成形得到外观质量良好的Ti-22Al-27Nb合金中空四层结构件,成形构件壁厚分布均匀。     

"相变-扩散钎焊(T/DB)"新工艺及其接头界面形貌

为减小相变超塑性扩散连接的循环次数,提出了一种新型焊接工艺"相变-液相扩散焊(T/DB)",即在待焊母材间预先放入液相扩散焊用的中间层,然后按传统相变超塑性扩散连接工艺施焊,但要求温度循环的峰值温度须同时大于母材的相变点与中间层的熔点.试验以低碳钢为母材,以镍基非晶箔带(BNi2)为中间层,进行了低碳钢的相变-扩散钎焊(循环3次)与液相扩散焊接(1200℃×3 min)的对比试验.结果表明相变-液相扩散焊所需温度循环次数少,接头无界面空洞,其接合线呈非平面状;而液相扩散焊接头的接合线较平直.分析认为,界面的起伏是母材的适度溶解与超塑性流变共同作用的结果;非平面状界面有利于增大金属-金属接触面积及扩散通道的面积,为获得合格接头做出了相应贡献.     

Superplastic Forming/Diffusion Bonding Without Interlayer of 5A90 Al-Li Alloy Hollow Double-Layer Structure

The hollow double-layer structure of 5A90 Al-Li alloy was fabricated by SPF/DB process in this study. The characteristics and mechanism of 5A90 Al-Li alloy with respect to superplasticity and diffusion bonding were investigated. Tensile tests showed that the optimal elongation of tensile specimens was 243.97% at the temperature of 400 °C and the strain rate of 0.001 s^?1. Effect of the surface roughness, bonding temperature and bonding time to determine the microstructure and mechanical properties of diffusion bonding joints was investigated, and the optimum bonding parameters were 540 °C/2.5 h/Ra18. Through the finite element simulation, it could be found that the SPF/DB process of hollow double-layer structure was feasible. The hollow double-layer structure of 5A90 Al-Li alloy was manufactured, showing that the thickness distribution of the bonding area was uniform and the thinnest part was the round corner. The SEM images of diffusion bonding joints showed that sound bonding interfaces were obtained in which no discontinuity existed.     

Advances in fabricating superplastically formed and diffusion bonded components for aerospace structures

Superplastic forming and diffusion bonding (SPF/DB) production hardware is being fabricated today for aerospace applications. Metal tooling is being used to bring the titanium sheets into contact so diffusion bonding can occur. However, due to material sheet and tooling tolerances, good bond quality is difficult to achieve over large areas. A better method for achieving DB is to use “stop-off” inside sealed sheets of titanium, which constitutes a pack, and then the pack is bonded using external gas pressure. A good method for heating the pack for this process is to use induction heating. Components using “stop-off” that were diffusion bonded first and then superplastically formed have shown much better bond quality than components that were produced using matched metal tooling. This type of tooling has been successful at bonding small areas as long as the exerted pressure is concentrated on the area where bonding is required. Finite element modeling is providing weight effect solutions for titanium SPF/DB aerospace structures. This paper was presented at the International Symposium on Superplasticity and Superplastic Forming, sponsored by the Manufacturing Critical Sector at the ASM International AeroMat 2004 Conference and Exposition, June 8–9, 2004, in Seattle, WA. The symposium was organized by Daniel G. Sanders, The Boeing Company.     

镍基合金超塑成形与扩散连接技术研究进展

本文对镍基合金超塑成形与扩散连接技术的研究概况及取得的研究成果进行了综述 ,并根据镍基合金在航空航天中的应用情况 ,对镍基合金超塑成形 /扩散连接 (SPF/DB)技术在航空航天工业中的应用进行了探讨与展望。     

采用新型加压介质的Al—Li合金SPF／DB工艺研究

本文针对目前超塑成形与扩散连接组合工艺（ＳＰＦ／ＤＢ）中普遍存在的模具气路设计复杂、时间—气压曲线难以控制等问题,提出了一种采用新型加压价质进行ＳＰＦ／ＤＢ的新工艺。文中给出了气体发生剂的选取原则,对Ａｌ－Ｌｉ合金在空气中的扩散连接提出了一整套工艺规范。文中所提出的工艺对Ａｌ－Ｌｉ合金外的其它材料也同样具有实用价值。     

钛合金两层大型构件SPF/DB关键技术问题及质量控制

超塑成形/扩散连接(SPF/DB)是一种低成本、高效益、近无余量的先进制造技术,钛合金两层SPF/DB构件在航空航天领域已获得广泛的应用。当构件尺寸较大且型面复杂时,在扩散连接、模具结构、工艺图形、表面质量等方面,将产生一系列新的影响零件质量的关键技术问题。该文针对技术难点进行数值模拟及工艺分析,根据分析结果采取相应的解决措施,并进行口盖验证试验和性能测试。结果表明,零件各项性能检测均满足设计要求,通过解决关键技术问题实现了对工艺过程及零件质量的精确控制。     

扩散连接接头区域元素浓度分布的数值分析

扩散连接接头区域元素浓度的分布是扩散连接技术中影响被连接材料的扩散，相变，界面反应及接头质量的重要因素，为此人们借助于计算技术。对其进行数值模拟，以便对扩散连接过程及质量进行预测与实时控制，针对异种材料的扩散连接过程，以热力学第二定律为基础，进行了扩散连接接头区域元素浓度分布的数值分析，建立了生成固溶体类型的界面反应模型，以使人们能够定性或半定量的分析扩散连接因素对接头性能的影响。利用耐热合金K5与耐热钢2Cr12NiMoV的扩散连接对建立的模型的试验验证表明，模型能够较好的反映元素的分布规律，可以为扩散连接工艺参数的制定提供一定的参考。     

高钒高速钢/35CrMo复合轧辊界面组织和性能研究

采用电磁半连续复合铸造法制成高钒高速钢35CrMo复合轧辊，研究了复合界面组织形貌特征和微区成分分布，测试了结合界面的力学性能。结果表明：界面上有厚度为40μm左右扩散层，层内显微组织为珠光体；邻接扩散层的合金钢侧组织为铁素体和珠光体，高速钢侧为马氏体基体上分布着VC颗粒。高速钢和舍金钢的显微硬度值分别为700HV和250HV，扩散层介于两者之间硬度值为350HV；冲击韧度值可达到100J／cm^2。该方法制备的复合轧辊界面具有良好的组织特征和力学性能，是冶金结合和扩散结合共同作用的结果。高钒高速钢35CrMo复合界面存在明显扩散层，且界面两侧发生成分扩散。结合区两侧显微硬度差别很大，但在界面处无突变。界面冲击韧度随高钒高速钢面积比的增加快速下降。     

相变扩散连接界面生成金属间化合物的数值模拟

在异种材料扩散连接的接头中,当界面上有脆性的金属间化合物产生时,接头往往表现出较差的力学性能。因此,从扩散连接的生产应用及扩散连接的理论研究出发,研究扩散连接接头的界面金属间化合物的生成规律,进而对其控制,是有着非常重要的现实意义的。扩散连接界面上金属间化合物的生成及成长机制是受扩散控制的反应扩散机制,而相变扩散连接中往往还伴随着相变,因此相变扩散连接的界面反应机制更为复杂。本文根据相变扩散连接的     

Solid-state reactive diffusion between Ni and W

Various alloys are interconnected with W using a Ni intermediate layer by the diffusion bonding (DB) technique. During solid-state heating in the DB technique, however, reactive diffusion occurs at the interconnection between Ni and W. In order to examine the kinetics of the reactive diffusion, sandwich Ni/W/Ni diffusion couples were isothermally annealed at temperatures of T = 1023-1173 K for various times up to t = 366 h. Owing to annealing, Ni₄W is produced as a layer at the Ni/W interface in the diffusion couple and grows predominantly towards Ni. The thickness of the Ni₄W layer increases in proportion to a power function of the annealing time. The exponent of the power function is close to 0.5 at T = 1173 K and gradually decreases with decreasing annealing temperature. Furthermore, grain growth takes place in Ni₄W due to annealing. Therefore, volume diffusion is the rate-controlling process for the growth of Ni₄W at T = 1173 K. At T < 1173 K, however, boundary diffusion contributes to the rate-controlling process, and the contribution of boundary diffusion increases with decreasing annealing temperature. On the other hand, a region alloyed with W is formed in Ni from the Ni₄W/Ni interface by diffusion-induced recrystallization (DIR). The growth rate of the DIR region is much greater than the penetration rate of W into Ni by volume diffusion, and the concentration of W in the DIR region at the Ni₄W/Ni interface is equal to the solubility of W in Ni. Such growth behavior of the DIR region was numerically analyzed using a mathematical model. The analysis indicates that the growth of the DIR region is controlled by the interface reaction at the moving boundary of the DIR region as well as the boundary diffusion along the grain boundaries across the DIR region under the present annealing conditions.     

日本关于固相扩散焊界面空洞收缩机理的研究

日本学者对固态扩散焊界面空洞收缩机理进行了系列研究：（1）提出了二维界面几何模型;指出界面空洞收缩是在塑性变形、粘塑性变形、界面扩散及体积扩散四大机制作用下实现的：并估算了各机制的作用大小,（2）在基于空位扩散的界面扩散的数值计算中,考虑了因界面扩散引起的刚性位移及在不同接合率下的空沿间隔2L的变化;另外还研究了空洞表面扩散快慢对界面扩散的影响。（3）首次提出了粘塑性变形机制的有限元模型,并发现在扩散焊后期拘束对空洞收缩速度有显著的抑制作用。     

爆炸焊接界面的结合机理

爆炸焊接界面虽然同时具有熔化、扩散和压力焊的特征 ,但熔化所产生的缝隙和”空洞物”大大削弱了界面的结合强度 ,在爆炸焊接过程中 ,要尽量消除熔化的影响 ,因此本文否定了爆炸焊接传统的熔焊机理 ;而扩散焊是压力焊的一种形式 ,同时扩散也只是界面由于高压产生结合的结果 ,而不是界面结合的原因 ,所以也不宜用扩散焊接解释爆炸焊接界面的成因。试验和理论研究表明 ,爆炸焊接是一种特殊的压力焊。为了获得没有熔化的微小波状的良好界面 ,爆炸焊接装药参数应取焊接窗口的下限。     

电场激活Ti/Ni扩散偶连接界面相变规律与力学性能的研究

本试验采用电场激活扩散连接技术(FADB)实现了Ti/Ni的扩散连接。研究了Ti/Ni两种材料发生界面扩散反应时新相的生成规律及其对连接强度的影响。利用扫描电子显微镜及能谱仪观察和分析了扩散层的显微组织、相组成和界面元素分布。采用万能试验机对扩散层的抗剪切性能进行了测试。研究结果表明,在电场作用下,Ti与Ni通过固相扩散形成了良好的冶金结合界面,界面处金属间化合物的生成次序依次为Ni3Ti、Ni Ti2、Ni Ti。当扩散温度≥750℃时,Ti表现出超塑性和良好的扩散性,促使扩散层中的Ni3Ti转变成富钛层,该富钛层的形成有利于接头强度的提高。界面的剪切强度随着电流的增大而增大,当电流为930~1200 A时,界面的剪切强度可达90.54 MPa。     

Interface effects during consolidation in titanium alloy components locally reinforced with matrix-coated fibre composite

An investigation has been made of diffusion bonding at the interface between a local reinforcing metal matrix composite and a monolithic engineering material. Diffusion bonding occurs during the consolidation of the composite during component manufacture. In this study, the composite is made up from Ti–6Al–4V titanium alloy coated SiC fibres, and the monolithic engineering material is also Ti–6Al–4V, but with a different microstructure.

An interface model is presented which takes account of diffusion bonding and which is able to describe the deformation behaviour at the interface between composite and monolithic material during composite consolidation. The model is developed from an existing diffusion bonding theory, and is implemented into finite element software.

The finite element simulations, and results of experiments, show that diffusion bonding can lead to localised deformation, the inhibition of consolidation, and a resulting inhomogeneous distribution of consolidated and unconsolidated regions during component manufacture. A further effect of the diffusion bonding is to increase the level of component distortion which results from the constraint imposed on the consolidating composite.

The interface model presented enables the simulation of practical forming processes so that process variables such as temperature and pressure can be chosen to ensure appropriate finished component properties.     

γ-TiAl基合金与异种合金扩散连接研究

主要对采用扩散连接（DB）或超塑扩散连接（SPF／DB）的方法，实现TiAl合金与异种合金（Ti-6Al-4V、40Cr钢和Ni基合金）固态连接的研究进行评述，探讨了连接工艺对连接界面显微组织及其连接件性能的影响。研究结果表明，扩散连接（或超塑扩散连接）能实现TiAl合金与异种合金高质量的连接。而扩散连接过程中，在扩散层产生的脆性相是导致焊件断裂发生在界面处的主要原因。采用中间层可有效避免脆性相的生成，而采用激光表面快凝处理，在拟连接表面获得细晶组织，可在较低温度下实现TiAl合金与异种合金的超塑扩散连接。     

键合时间对粗铝丝超声引线键合强度的影响

试验研究了不同超声功率条件下,键合时间对粗铝丝引线键合强度的影响规律.试验中记录了每种键合试验的键合时间,采集了每一个键合点的剪切测试力作为键合点抗剪强度的表征,记录了每个键合点的状态.结果表明:(1)在小超声功率条件下,键合强度对键合时间敏感;在大超声功率条件下,敏感性下降;(2)短键合时间条件下主要键合失败形式为剥离和无粘接,表明键合界面的原子扩散不够;(3)大超声功率长键合时间条件下的键合失败形式多为根切,表明键合界面的原子扩散虽然足够,但长时间的超声振动也会使粗铝丝产生疲劳断裂,形成过键合.     

聚晶金刚石复合体复合机理的研究

本文对超高压合成的PDC,采用SEM、EDS等分析方法研究了：PCD界面结构,分析了粘结相钴扩散规律及聚晶金刚石复合体复合机理。实验结果表明,WC—Co与金刚石界面的结合实际上就是WC-Co-金刚石界面的结合,WC—Co与金刚石界面的结合强度不仅与界面钴含量有关,而且与界面上的钴的组织结构有关：D—D结合区域中的D—D结合界面处钴浓度远低于D-Co—D结合区域的晶粒间界钴的浓度,说明D-D结合区域和D—Co—D结合区域的晶粒间界中钴的存在形式是不同的。