铝/钛异种合金激光深熔钎焊试验分析

采用3500W板条式扩散冷却CO2激光器,利用激光深熔钎焊原理对3mm厚6061铝合金和钛合金进行异种金属激光焊接.聚焦激光作用在铝合金一侧为深熔焊,熔化的铝合金浸润钛合金界面形成钎焊接头.拉伸试验发现,断裂均发生在界面处,通过Olympus金相显微镜观察发现断口存在部分未熔合.结果表明,降低焊接速度,并采用合适的偏焦量,负离焦量和偏转角度可以改善界面的熔合.     

铝合金空气炉中钎焊的试验研究

采用不同加热制度在空气炉中进行6063铝合金的钎焊试验，并对钎焊接头进行了外观、金相及剪切强度的检测分析。结果表明，在适当的工艺条件下采用空气炉中加热钎焊铝合金是可行的。其工艺要素是，被焊面要清理充分，用夹具夹紧使被焊面紧密贴合以及快速加热升温。     

铝及铝合金钎焊技术的研究现状

综述了近年来铝及铝合金钎焊在钎焊方法、钎料及钎剂三个方面的技术发展现状，分别介绍了它们各自的发展方向。指出铝及铝合金的钎焊问题是近年来研究较多、发展较快的研究领域之一，铝及铝合金钎焊技术应用前景广阔。     

Advances in brazing of creep-resisting alloys

The problems of brazing of creep-resisting nickel and intermetallic alloys based on titanium aluminide are investigated. Advantages of using adhesion-active brazing alloys based on Ni–Cr–Zr, Pb–Ni–(X), Ti–Zr–Fe, and Ti–Zr–Mg systems for brazing are described.     

钛合金用钎焊料的发展评述

概述了钛合金用的银基、钛基、铝基钎焊料的发展和研究状况，并分析和讨论了这３种钎焊料各自的优缺点以及Ｔｉ合金用钎焊料的发展趋势。     

国际钎焊技术最新进展

总结了最近3年来的4次国际焊接会议有关钎焊技术的最新进展.介绍了轻合金(包括铝合金、钛合金、镁合金)用新型钎料(或钎剂),锡基、Au-Ge等低温钎料,以及陶瓷钎焊用高温钎料的最新研究成果;新颖的纳米复合钎料和纳米叠层箔带中间层扩散焊技术的研究得到了关注;特殊的钎焊新工艺,包括超声波辅助钎焊、气体保护电弧钎焊、等离子钎焊...     

铝/钛异种合金激光熔钎焊接头特性

以C02激光为热源，以A1Si12焊丝为填充材料，对Ti-6Al-4V钛合金和5056铝合金异种材料激光熔钎焊进行研究，采用SEM、EDS、XRD和金相显微镜分析接头的微观结构特征，通过拉伸实验评定接头的力学性能。研究结果表明：所得接头具有熔焊和钎焊双重性质，即铝母材局部熔化，为熔化焊，而钛母材与焊缝金属之间存在金属间化合物层钎焊界面；钎焊界面上部的金属间化合物层组成复杂，可分为2层，即呈针状或芽状的Ti-Al-Si系金属间化合物层和以Ti-Al系金属间化合物为主的连续层；钎焊界面下部的金属间化合物层较薄；拉伸试样断裂倾向于发生在紧邻钎焊界面的焊缝上，平均抗拉强度为298．5MPa。     

高品质高可靠性钎料的技术发展及应用

结合国际高品质钎焊材料的研究现状和未来发展方向,总结了新型铝基钎料、银基钎料、铁基钎料及钎焊技术的国内外最新研究进展与应用成果.AlSiCu基低熔点钎料具有较高的强度和较好的耐腐蚀性能,特别是添加微量稀土元素后能通过变质作用降低表面张力和促进界面元素扩散,适用于高强度铝合金、铝-钢、钛合金的连接.新颖的纳米多层膜低温钎料及涂层制备技术取得一系列新的研究结果,与钎焊技术相结合具有良好的应用前景;特殊的钎焊新技术,如超声波辅助钎焊、等离子-激光复合钎焊为实现无钎剂和非真空环境下材料的液相连接提供了新的解决方案.     

Large gap joining of Ti–6Al–4V alloy with mixed powder interlayers

Abstract

Titanium based brazing alloys containing chromium, iron, copper, and nickel as β stabilisers have been studied for joining the titanium alloy Ti–6Al–4V. Two of these alloys were selected for use in producing large gap joints. The first brazing alloy, Ti–12Zr–14Cr–12Cu–12Ni (type 1), can be used to braze Ti–6Al–4V below its β transus temperature. Joints of thickness up to 150 μm can be made in a normal brazing cycle without prolonged holding. The interlayer consists of a β titanium alloy with no precipitation of intermetallic compounds. The second brazing alloy, Ti–12Zr–14Cr–6Fe–5Cu–5Ni (type 2), has to be brazed above the β transus temperature of Ti–6Al–4V. Its powders were mixed with pure titanium and Ti–6Al–4V powders and the mixture was used as the joining interlayer. Interlayers 5 mm in thickness were used to produce joints for microstructural examination and mechanical testing. It was found that residual pores in the interlayers were related to the amount of the brazing alloy in the interlayer. A fully dense interlayer could be obtained with 60 wt-% brazing alloy in the interlayer. The as bonded joints revealed tensile strength equal to 50% of that of the base metal. Diffusional treatment of the joints improved the joint efficiency to about 70%, compared with the base metal.     

Current state and prospects of development of welding technologies in the aircraft industry

The results of investigation of the bonding zone in the titanium–aluminium composite produced by explosion welding in conditions close to the upper boundary of weldability are presented. Local heterogeneous alloys consist of a solid solution matrix based on aluminium with aluminium nitride particles. The increase in deformation energy resulted in the increase in the size of the area, the volume of the alloys and the volume content of the aluminides. Formation of the alloys did not reduce the maximum strain capacity of the joint.     

Brazing alloys for marine service

Abstract

The microstructure of brazing alloys to B.S. 1845 and to certain proprietary specifications is reviewed and related to corrosion performanee in sea water on joints with copper, 70/30 cupro-nickel and 7% aluminium bronze. The factors influencing corrosion are illustrated and discussed and recommendations are made as to the suitability of various braze metal-parent metal combinaiions. Of seven brazing alloys tested with the three parent materialsi only two were completely satisfactory, two could be used within certain limitations and three were unsatisfactory.     

细晶铝锭熔炼的6063铝合金铸态组织与性能研究

细晶铝锭是采用纯铝的电解设备,通过向铝电解槽中添加TiO2,直接电解生产的晶粒细化的铝锭。采用细晶铝锭熔的6063铝合金与AlTi5B1、AlTi5中间合金细化的6063铝合金铸态组织性能进行对比研究。结果表明:AlTi5B1中间合金细化效果最好,AlTi5中间合金细化效果最差,细晶铝锭的细化效果居中;6063铝合金铸态组织硬度,在钛含量低于0.05%时,主要由Mg2Si含量决定,晶粒大小对硬度的影响较小。     

Combined anodic/cathodic transient currents within nucleating pits on Al–Fe alloy surfaces

Pit nucleation and metastable growth on microelectrodes of aluminium and some Al alloys in chloride solution below the pitting potential are described by recurring current transients. Pit nucleation is a sharp, violent event and is observed repeatedly on all materials tested: pure aluminium, titanium and iron binary aluminium alloys, and alloy 1050A. At the imposed electrode potential, current transients due to pit nucleation recorded for pure aluminium and a solid solution titanium binary alloy are exclusively anodic. Those from alloys containing iron intermetallics sometimes exhibit both anodic and cathodic wings. The cathodic wing is due to transient hydrogen evolution at sites which border iron-rich intermetallic particles: these are preferred pit nucleation sites.     

Evolution of microstructure and phase composition of joints with ultrasonic-assisted resistance brazing

ABSTRACT

Zn–2Al alloy is used as a filler metal for brazing of aluminium 6063 alloys by ultrasonic-assisted resistance brazing (RB) technology. The evolution of the microstructure and phase composition under the effects of the electric field and ultrasonic vibration were studied. The results show that ultrasonic cavitation can remove the existing oxide films effectively and inhibit element segregation, which help obtain joints with good metallurgical bonding. In comparison to RB joints, which exhibit a coarse dendritic structure, a uniform dendritic structure was obtained in the ultrasonic-assisted resistance joints. Furthermore, the combined electric and ultrasonic field has a significant effect on grain size and on dissolution during brazing. With the application of ultrasonic vibration, the diffusion between the base metal and the Zn–2Al filler metal intensifies.     

Ti/Al异种合金电弧熔钎焊接头温度场与界面微观组织

采用交流TIG焊电弧与AlSi12焊丝实现了TC4钛合金与LF6铝合金熔钎焊连接,通过有限元软件分析接头温度场,并利用扫描电镜观察接头钎焊界面的微观组织特征.结果表明,接头温度分布极不均匀,钛侧梯度大高温区窄,铝侧梯度小高温区范围广,冷却时高温区逐渐向钛侧偏移.当钨极正对钛钝边时,等温线平行于钎焊界面,温度分布均匀,有利于形成组织均匀的界面反应层.冷体熔钎焊加速了钎焊界面的冷却,降低了钛的溶解量,可抑制金属间化合物的生长.化合物层形貌由空冷时的锯齿状转变为胞状生长.     

低钛铝合金的电解生产与晶粒细化

在电解低钛铝合金的工业化生产试验中，研究和对比了电解加钛和熔配加钛低钛铝合金的晶粒细化效果及其衰退行为。结果发现：电解质中添加少量TiO2对电解槽铝产量和电流效率影响较小，二者分别维持在1200kg和92％左右，钛的吸收率在95％以上所生产的合金钛含量稳定，晶粒细化效果明显，晶粒尺寸随钛含量的变化趋势与熔配加钛合金相同；钛含量在0．1％～0．2％范围内时，电解加Ti合金晶粒细化效果的抗退化能力比熔配加Ti合金的强。     

Untersuchung der Einwirkung einer Reaktionsdiffusion und Versprödung auf die Rißbildung von Titanlegierungen bei erhöhter Temperatur

Influence of surface reaction diffusion at high temperatures on the formation of brittle fractures in titanium alloys Heat resistant titanium alloys, which in almost all cases contain aluminium as an additional element, exhibit a tendency to brittle fractures at high temperatures, whereby the optimum elongation of the samples decreases with a longer experimental time. Examinations of the alloys TiAl5Sn2, 5, TiAl6V4, TiAl7Mo4 and TiAl9V3 with help of scanning electron probe microanalysis have shown that aluminium, as a consequences of reaction with the atmosphere becomes enriched at the surface. Because of teh enrichment of aluminium a super lattice of the a-solid solution is formed, which exhibits a different deformation mechanism from the a-solid solution free from super lattice Diffusion of the aluminium occus mainly along the grain boundaries, which also causes these to be enriched with aluminium and has an inclination to be brittle. In allosy exhibiting a polygonal grain the fractures due to brittleness are intercrystalline because of the aluminium enrichment. If the alloys are cold-formed before stress at higher temperatures the grain boundaries are destroyed and intercrystalline fracture can no longer occur. The brittle zone occurs only on the surface, and the continuation of the fracture can only take place within this area. In this case no brittleness can be observed.     

锡镀层对BAg50CuZn钎料性能的影响

以BAg50CuZn钎料为研究对象,在其表面电镀锡,借助扫描电镜(SEM)观察锡镀层的表面形貌,采用差热分析仪(differential scanning calorimetry,DSC)和润湿试验炉分析锡镀层对合金钎料熔化温度和润湿性能的影响,并对镀覆锡后合金钎料的成分进行了讨论.结果表明,随着钎料表面镀覆Sn元素含量增加,合金钎料的DSC吸热峰向左偏移、熔化温度降低,钎料的润湿铺展性能呈上升趋势.在镀覆Sn元素含量为4.8%(质量分数)时,合金钎料表面锡镀层平整、致密,钎料的铺展面积最大,为236 mm2.镀覆元素Sn后的钎料中,Ag,Cu,Zn元素含量均减少,元素含量降低幅度大小顺序依次为Cu,Ag,Zn.     

铝/钛异种金属冷金属过渡熔钎焊接头分析

以ER4043的铝焊丝对6061铝合金和TA2纯钛进行CMT熔钎焊,采用金相显微镜、扫描电镜(SEM)和能谱分析仪(EDS)分析了焊接接头的微观组织特征,并通过拉伸试验对接头进行了力学性能的评定. 结果表明,焊接接头具有熔焊和钎焊双重性质:铝母材局部熔化,与熔化的焊丝金属混合后凝固形成焊缝;而没有熔化的钛母材通过Ti原子的扩散与焊缝金属形成金属间化合物结合层的钎焊界面. 钎焊界面处反应层可分为靠近钛板一侧的连续层Ti₃Al和向焊缝内部生长的锯齿状的反应层TiAl₃. 当钛板坡口角度为30°时,钎焊界面化合物生长均匀良好,接头会断裂在铝母材的热影响区,最高抗拉强度达到197.5 MPa.     

Ti—30Ni钎缝的界面反应及金相观察

研究了钛在真空钎焊过程中钎焊温度,保温时间及装配间泽界面反应程度的影响。钎焊过程中钎料组元镍和基体金属钛之间存在着明显的相互扩散过程,即基体金属钛向钎料的溶解和钎料组元镍向基体钛的扩散。镍向钛基体扩散的结果形成了一个明显的扩散层,镍在扩散层内主要以Ｔ２Ｎｉ化合物形式存在,并且存在较大的晶间渗入倾向。