C/SiC复合材料表面状态对其与Nb钎焊的影响

采用等原子比Ti-Ni复合箔对C/SiC复合材料与Nb进行了真空反应钎焊,研究了焊前C/SiC表面状态对接头界面组织和力学性能的影响.结果表明,线切割态的C/SiC与Nb的接头界面(Ti,Nb)C反应层呈现锯齿状,而抛光和砂纸打磨状态的C/SiC接头界面处的反应层平直.锯齿状的界面反应层降低了界面处的应力集中程度,有助于提高接头的力学性能,使得线切割态的C/SiC与Nb的接头强度明显高于抛光和打磨状态的接头,达到188MPa.线切割态的C/SiC与Nb的接头断裂同时发生在C/SiC母材、界面和钎缝中,而抛光和打磨状态的C/SiC与Nb的接头断裂主要发生在界面处.     

INTERFACIAL REACTION BEHAVIOUR AND JOINT STRENGTH OF TiCp/Si3N4 COMPOSITE BONDED WITH Al FOIL

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过渡层对铝/钢FSB接头性能和组织的影响

通过镀覆镍及Ni/Cu复合过渡层,采用锌作为钎料,对工业纯铝和低碳钢板进行了搅拌摩擦钎焊(FSB)连接. 对焊接接头进行了拉剪和抗撕裂试验,并与无任何过渡层接头进行了对比. 用扫描电镜及能谱对接头界面形貌和微观组织进行了分析,研究分析了过渡层对铝/钢FSB接头力学性能和微观组织的影响. 结果表明,过渡层能有效阻止脆性Al-Fe金属间化合物的生成,增加了接头抗撕裂载荷强度,提高接头的力学性能.     

Mechanisms of joining aluminium A6061-T6 and titanium Ti–6Al–4V alloys by cold metal transfer technology

Abstract

Cold metal transfer (CMT) welding–brazing joining of Ti6Al4V and Al A6061-T6 was carried out using AlSi₅ wire. The joining mechanisms and mechanical properties of the joints were identified and characterised by scanning electron microscope, energy dispersive spectroscopy and tensile–shear tests. Desired CMT joints with satisfied weld appearances and mechanical properties were achieved by overlapping Ti on the top of Al. The joints had dual characteristics of a welding joint on the aluminium side and a brazing joint on the titanium side. Three brazing interfaces were formed for the joint, which increased the strength of the joint. An intermetallic compound layer was formed at the brazing interface, which included Ti₃Al, TiAl and TiAl₃. Two different fracture modes were also observed: one fractured at the welding/brazing interface and weld metal and the other at the Al heat affected zone (HAZ). Clearly, the joints fractured at the Al HAZ had higher tensile strength than those fractured at the welding/brazing interface and weld metal.     

辅助电流对Cu/Al大功率超声波焊接的影响

为获得更高质量的Cu/Al异质金属接头,开展了Cu/Al电流辅助大功率超声波焊接工艺试验,研究了辅助电流对Cu/Al超声波焊接的界面温度、材料塑性流动、界面中间相(IMC)分布及接头力学性能的影响。结果表明,复合焊件成型良好,其接头抗拉剪力为3030N,接头的断裂模式为韧性-脆性复合断裂。在同样的焊接时间0.2s内,随着电流的增大,Cu/Al界面温度增加,金属塑性流动以及界面扩散也随之增强,这说明辅助电流能明显促进界面冶金;相比长时间0.4 s的超声波焊接,辅助电流能在保证界面温度、材料塑性变形的前提下,能明显减薄界面IMC层的厚度,这是电流增强Cu/Al接头的主要物理机制。研究结果为优化Cu/Al复合焊接头强度提供了参考。     

附加几何形貌特征对Steel/CFRP无铆连接接头性能的影响

基于无铆连接技术,提出对钢板和碳纤维预浸料进行热冲压局部成形的Steel/CFRP连接工艺,设计了平板型及具有矩形凹槽、弧形凹槽、分布式圆柱形凹坑、分布式球形凹坑等几种不同附加几何形貌特征的Steel/CFRP连接接头。采用Hashin损伤准则及内聚力模型,通过系列有限元仿真实验,研究了有效粘结长度、不同附加几何形貌特征、尺寸及分布对接头性能的影响。仿真与拉伸剪切实验结果对比分析发现:仿真建模时所采用的理想结合界面假设,以及对胶黏剂性能、局部成形界面内应力重新分布的忽略,是造成仿真结果与实验结果出现较大出入的主要原因,可以通过对附加几何形貌特征参数和连接工艺条件优选,促使接头处形成理想的结合界面和机械镶嵌作用,以提高Steel/CFRP接头性能。     

先进功能材料钎焊连接研究进展

以复相陶瓷、纤维增强陶瓷基复合材料以及热电材料为例,从钎料成分设计、钎缝界面组织调控、接头残余应力缓解以及钎焊接头性能评测等角度,讨论了近年来发表的研究成果. 结果表明,在钎料中添加活性元素以及对母材表面改性的方法,能够有效改善钎料润湿性和界面结合强度;对于界面元素扩散以及母材过渡溶解的问题,可以设计制备复合钎料或阻隔层进行解决;接头残余应力的大小受材料热膨胀系数差异的影响较大,目前已提出了多孔中间层、梯度复合层以及母材表面机械加工等多种创新方法,但研究成果的应用仍停留在小尺寸样件,对于缓解大尺寸接头的残余应力问题仍有待解决. 最后对相关研究方向进行了总结和展望,期望推动航空航天构件连接的发展进程.     

Comeld～TM Joints: A Novel Technique for Bonding Composites and Metal

Current and future structural applications for composite laminates frequently involve design solutions combining composite laminates and metal; the materials must be joined. Two conventional means of joining are available: mechanical joining and adhesive bonding. Both methods have critical disadvantages. A novel surface treatment for metals developed at TWI, Surfi-Sculpt, leads to the formation of surface protrusions on metal surfaces. These protrusions are typically 1.0 mm high and 0.6 mm in diameter. The...     

铁素体-奥氏体异种钢接头的界面组织及力学性能

为提高电站锅炉过热器铁素体－奥氏体异种钢焊接接头的高温蠕变断裂强度和服役寿命，设计了专用的镍基填充材料及组合焊接接头。通过对不同焊缝接头的高温蠕变力不试验，焊缝界面组织变化分析，碳扩散和热应力的测试分析，认为在高温低力的条件下，接头焊缝界面及热影响区碳元素扩散迁移和碳化物聚集是影响接头蠕变断裂强度的重要原因。     

Diffusional bonds in laminated composites produced by ECAP

The microstructure, diffusional and mechanical bonding behavior and microhardness distribution of laminated composites fabricated by ECAP process were investigated. Al-Cu and Cu-Ni laminated composites were produced by ECAP process up to 4 passes at room temperature and high temperature (300 °C). The results of microstructure characterization by SEM and shear strength test revealed that the joints between the layers of 4-pass ECAPed samples were considerably stronger than those of 1-pass ECAPed samples due to tolerating higher values of plastic deformations during ECAP. Furthermore, shear strength data showed that increasing ECAP temperature caused a notable increase in shear strength of the specimens. The reason lies in the formation of diffusional joint between the interface of both Al/Cu and Cu/Ni layers at high temperature. The shear bonding strength of ECAPed Cu/Ni/Cu composite at high temperature was remarkably higher than that of ECAPed Cu/Al/Cu composite.     

Ni/Si中间层对铝/钢激光焊接头组织与性能的影响

研究了以Ni箔以及预置Si粉的Ni箔为中间层的铝/钢异种金属激光焊行为. 系统考察了不同激光功率下预置Si粉的Ni箔中间层对铝/钢异种金属激光焊接头组织与性能的影响. 结果表明,加入预置Si粉的Ni箔做复合中间层时,与只添加Ni箔片做中间层时相比,焊接接头的最大剪切力明显提高,其中激光功率为2 150 W时焊接接头的最大剪切力提高至1 307.96 N;Si粉的添加增加了熔池的流动性,并使得铝/钢界面的物相组成、元素分布和微观组织形态发生了改变;焊缝区生成了Fe-Si及Al-Si二元新相,有效抑制了Fe-Al二元脆性相的生成,改善了铝/钢的焊接性. 因此,预置Si粉的Ni箔复合中间层的加入,可以有效地改善铝/钢异种金属激光焊过程中的冶金反应,进而提高焊接接头的力学性能.     

The Nature of Interfaces in Al-1050/Al-1050 and Al-1050/Mg-AZ31 Couples Joined by Magnetic Pulse Welding (MPW)

The microstructure and the phase composition of the interfaces of Al-1050/Al-1050 and Al-1050/Mg-AZ31 magnetic pulse welding (MPW) joints were characterized by SEM and TEM analyses. The mechanical properties were tested by nanoindentation. Properties of the Al-1050/Al-1050 interface joint were established. The interface is almost free from Al₃Fe precipitates, which are present in the base metal. The hardness value is higher than that of the base metal; however, values of the Young’s modulus of the interface and base metal are similar. It was suggested that the interface evolution in the Al-1050/Al-1050 system includes local melting and rapid solidification of the base materials. A wavy shaped heterogeneous interface was detected in the Al-1050/Mg-AZ31 joints. Some areas are free from visible intermetallic phases (IMPs), while others contain pockets of relatively coarse intermetallic precipitates. The presence of a relatively large fraction of globular porosity at the interface indicates that local melting takes place in the course of MPW. TEM characterization of regions free of IMPs at the interface reveals regions consisting of fcc supersaturated Al-Mg solid solution, apparently formed as a result of local mechanical alloying during MPW. In other regions, the composition and structure correspond to the Mg₁₇Al₁₂ phase, which was probably formed by local melting and rapid solidification.     

消除应力回火对30CrMnSiNi2A真空电子束焊接头组织和力学性能的影响

针对30CrMnSiNi2A超高强度钢结构件真空电子束焊后消除应力回火工艺,开展了重复回火对锁底焊接接头最终热处理状态的组织与力学性能影响研究。试验结果表明,焊接零件分别经过一次、三次消除应力回火,其最终态拉伸性能与直接最终热处理30CrMnSiNi2A原材料相比有少量提升,同时焊缝的拉伸性能略高于母材;原材料、一次消除应力焊件、三次消除应力回火焊件终态显微组织均为板条状马氏体,除组织均匀性和马氏体形貌略微变化外,无显著的组织及成分差异;相比于母材的疲劳极限,一次消除应力回火接头疲劳极限降低了11%,三次消除应力回火接头疲劳极限降低了18%。创新点：(1)掌握了消除应力回火对接头拉伸性能和疲劳性能的影响规律。(2)结合微观组织分析,对影响机理进行了研究。     

Influences of fine pitch solder joint shape parameters on fatigue life under thermal cycle

1 INTRODUCTION The electronicer industry is driven mainly by the demand for“smaller ,faster ,higher complexi- ty ,lower power consumption and cheaper”[1]. To meet these needs , the demand for smaller size , higher density and higher heat dissipationintegrat- ed circuit (IC) chips is on the rise . With the requirements of high performance and small pack- age size ,the design of IC chips is headed toward higher pin count ,smaller pad size and fine pitch; consequently ,the fine pitch tech…     

铝合金与不锈钢的过渡层钎焊

铝合金与不锈钢的物化性能相差很大，两者的直接连接易于在界面上生成Al和Fe的脆性化合物。作者用试验的方法研究了LF3铝合金与0Cr18Ni9不锈钢的Ni／Cu过渡层钎焊的工艺方法以及接头的组织与力学性能，并对各连接界面进行了机理分析。对钎缝的界面做剪切试验、X射线衍射、扫描电镜(SEM)和透射电镜(TEM)等分析发现，镀层与钎料等各界面连接紧密，特别是钎缝与母材之间没有生成脆性Al-Fe金属间化合物。由此得出结论，面心立方结构的Ni／Cu电刷镀层能有效地阻挡Al、Fe等原子扩散，钎缝与镀Cu界面上虽然生成了少量的AlCu3，但由于组织不连续，没有大幅度降低钎缝的剪切强度。通过过渡层钎焊，实现了LF3铝合金与0Cr18Ni9不锈钢的复合连接．满足了工程需要。     

V/Nb复合中间层热等静压扩散连接钢/钨接头的组织与性能

采用V/Nb复合中间层成功实现了钢/钨热等静压扩散连接,并对高温低压(1 050 ℃, 20 MPa)和低温高压(950 ℃, 100 MPa)条件下形成的接头界面结构及连接强度进行了探究. 结果表明,高温低压组和低温高压组接头均呈W/Nb/V/钢四层结构,抗剪强度分别为96.9 MPa和104.2 MPa,断裂位置均为无明显化学反应发生在Nb/V界面. 与高温低压组相比,降低连接温度并提高连接压强在一定程度上有助于形成高致密度的连接接头,但不能促进薄弱界面(Nb/V)的元素扩散并显著提高接头的连接强度.     

镁合金与异质材料焊接接头界面行为及研究焊接性

对异质变形镁合金、镁合金和铝合金及镁合金和钢铁之间的焊接接头异质界面特点进行了分析,阐述了镁合金与其它金属之间的焊接性.通过新型焊接方法及填允金属的设计,能够有效地改善镁合金与异质金属间的界面组织结构特点,元素分布特征,进而实现提高焊接接头强度的日的.文中还揭示了镁合金与其它金属在焊接过程中所体现出来的界面行为特征,为镁合金和其它金属的连接奠定了基础.     

Cu-Ti+Mo连接2D C/SiC复合材料与GH783的接头微结构与性能

采用Cu-Ti+Mo复合焊料,在真空条件下对2D C/SiC复合材料和GH783镍基合金进行连接,分析接头的显微组织结构,研究Mo含量对接头组织及性能的影响.结果表明:接头由界面反应层、应力缓解层、软金属层和扩散层4个区域组成,接头致密,无孔洞、裂纹等缺陷.随着Mo含量的增加,接头的连接强度不断增加:当Mo含量为15％(体积分数)时,接头连接强度达到最大( 141 MPa);当Mo含量大于15％时,接头的连接强度开始下降.Mo的加入,缓解了接头的残余应力、抑制了Ti对C/SiC的过度侵蚀,从而有效提高接头的连接强度.     

Al-Si-Cu合金粉末扩散钎焊Al/Cu接头组织及性能

采用Al-Si-Cu合金粉末扩散钎焊铝铜异种金属,采用SEM,EDS和XRD分析接头微观组织结构,结合三元相图分析了接头形成机理,最后检测了接头力学性能.结果表明,在连接温度530℃,保温时间60 min,压力为1MPa时可形成均匀致密的接头,接头中存在大量条状和鱼骨状的Al-Si-Cu共晶组织,中间层与两母材结合界面处的组织结构不同,在靠近铜侧界面存在三种层状金属间化合物,其成分依次为Cu₃Al₂,CuAl和CuAl₂,在靠近铝侧界面存在一个扩散区,没有形成层状金属间化合物.接头的抗剪强度随保温时间的变化而变化,在保温60 min时达到35 MPa.     

连接条件对00Cr25Ni7Mo3N双相不锈钢扩散连接的影响

利用热模拟试验机并结合扫描电镜(SEM)对00Cr25Ni7Mo3N超级双相不锈钢的超塑扩散连接进行实验研究,对不同连接条件下的孔洞形貌、界面组织进行相应的分析。研究结果表明,超塑性扩散连接试样的界面结合强度随扩散连接压力的增大、表面质量的提高及连接时间的延长而增大。扩散连接在连接温度1100℃时,连接压力为10MPa～20MPa;待连接表面经精磨处理后,连接时间10min～20min的条件下,可实现焊合率为96%～98%的扩散连接,且连接试样的初始连接界面消失,界面孔洞基本闭合,界面剪切结合强度达到407MPa～413MPa。