TLP bonding of SiCp/2618Al composites using mixed Al–Ag–Cu system powders as interlayers

Mixed Al–Ag–Cu and Al–Ag–Cu–Ti powders were used as interlayers for transient liquid phase diffusion bonding (TLP bonding) of SiC particulate reinforced 2618 aluminum alloy matrix composite (SiCp/2618Al MMC). The results show that by using mixed Al–Ag–Cu powder with the eutectic composition as an interlayer, SiCp/2618Al MMC can be TLP bonded at 540 °C, however, the joining layer is porous. Adding a certain amount of titanium into the Al–Ag–Cu interlayer, the TLP bonding quality can be improved. The titanium added into the Al–Ag–Cu interlayer has an effect of shortening the solidification time of the joining layer, thus decreasing SiC particles from the parent materials entering into the joining layer. The joints bonded using Al–Ag–Cu–Ti interlayers have a maximum shear strength of 101 MPa when 2.1% titanium is added.     

Sn3.0Ag0.5Cu3.0Bi钎料对化学镀镍SiCp/6063Al复合材料真空钎焊接头组织和性能的影响

采用Sn3.0Ag0.5Cu3.0Bi软钎料对镀镍后的两种不同体积比SiC_p/6063Al复合材料进行真空钎焊。通过SEM、剪切试验等方法分析了化学镀镍后SiC_p/6063Al复合材料真空钎焊接头的显微组织以及保温时间对接头性能的影响。结果表明:两种不同体积比SiC_p/6063Al复合材料真空钎焊后的焊缝组织致密,钎料对镀镍复合材料的润湿性良好;在270℃、保温35min的钎焊工艺下,钎焊接头的剪切强度最大值为38.3 MPa;钎料中的Sn、Cu元素能够与复合材料表面的Ni层发生化学反应,实现钎料与母材的冶金结合;镀镍后SiC_p/6063Al复合材料真空钎焊接头断裂形式为韧性断裂为主的混合断裂,断裂主要发生在钎料内部,部分发生在镀镍层与钎料的结合处。     

Transient liquid-phase bonding of alumina and metal matrix composite base materials

Transient liquid-phase (TLP) bonding of aluminium-based metal matrix composite (MMC) and Al2O3 ceramic materials has been investigated, particularly the relationship between particle segregation, copper interlayer thickness, holding time and joint shear strength properties. The long completion time and the slow rate of movement of the solid–liquid interface during MMC/Al2O3 bonding markedly increased the likelihood of forming a particle-segregated layer at the dissimilar joint interface. Preferential failure occurred through the particle-segregated layer in dissimilar joints produced using 20 and 30 μm thick copper foils and long holding times (≥20 min). When the particle-segregated layer was very thin (<10 μm), joint failure was determined by the residual stress distribution in the Al2O3/MMC joints, not by preferential fracture through the particle-segregated layer located at the bondline. Satisfactory shear strength properties were obtained when a thin (5 μm thick) copper foil was used during TLP bonding at 853 K. This revised version was published online in November 2006 with corrections to the Cover Date.     

Effects of Al–8.5Si–25Cu–xY filler metal foils on vacuum brazing of SiCp/Al composites

Rapidly solidified Al–8.5Si–25Cu–xY (wt-%, x?=?0, 0.05, 0.1, 0.2, 0.3, 0.4, and 0.5) foils were used as filler metal to braze Al matrix composites with high SiC particle content (SiCp/Al-MMCs), and the filler presented fine microstructure and good wettability on the composites. The joint shear strength first increased, then decreased and a sound joint with a maximum shear strength of 135.32?MPa was achieved using Al–8.5Si–25Cu–0.3Y as the filler metal. After Y exceeded 0.3%, a needle-like intermetallic compound, Al3Y, was found in the brazing seam, resulting in a dramatic decline in the shear strength of the brazed joints. In this research, the Al–8.5Si–25Cu–0.3Y filler metal foil was found to be suitable for the brazing of SiCp/Al-MMCs with high SiC particle content.     

Auger electron spectroscopy of high-speed-deformed Ni/Cu layers

Ni/Cu double- and multilayers subjected to high-speed deformation were investigated by Auger electron spectroscopy (AES) using depth profiling. Ni and Cu thin films were alternately deposited on a 0.3 mm thick Ni substrate using RF magnetron sputtering. The thickness of the double-layer was 90 nm, while that of the multilayer was 160 nm. High-speed compression was performed using bullet masses from 30.0 to 57.4 g at varying bullet speeds between 16.8 and 48.5 m s⁻¹. The strain rate ranged from 6.7×10⁴ to 8.4×10⁵ s⁻¹. Upon high-speed deformation, the thickness of the Ni/Cu double-layer was reduced to about 80% of its original value. The Cu thin film was compressed to a greater extent relative to the Ni thin film (by about 15%), which may be due to the difference in malleability between the two metals. At a strain rate of 8.4×10⁵ s⁻¹, the Ni/Cu double-layer virtually disappeared. Ni/Cu interdiffusion was enhanced by high-speed deformation. The degree of interdiffusion appeared to be greater at lower strain rates. Cu_0.5Ni_0.5 and Cu_0.75Ni_0.25 thin film alloys formed in the high-speed-deformed multilayer sample, indicating that high-speed compression could potentially be used to prepare thin film metal alloys.     

高体积比SiCp/6063Al复合材料的铝基钎料制备及钎焊工艺研究

采用快速甩带技术制备了(Al-10Si-20Cu-0.05Ce)-1Ti(质量分数/％)急冷箔状钎料,并对60％体积分数的SiCp/6063Al复合材料进行真空钎焊实验,然后对钎料及接头的显微组织与性能进行测定和分析.结果表明,急冷钎料的微观组织细小、成分均匀,厚80～90μm,主要包含Al、CuAl2、Si和Al2Ti等相.当升高钎焊温度(T/℃)或延长保温时间(t/min),SiCp/钎料界面的润湿性改善,6063Al基体/钎料间互扩散和溶解作用增强,接头连接质量逐渐提高.当T=590℃、t=30 min时,接头抗剪强度达到112.6MPa;当T=590℃、t=50 min时,少量小尺寸SiCp因液态钎料排挤而分散于钎缝,因加工硬化而使接头强度递增7.3％.然而,当T≥595℃、t≥60 min时,SiCp偏聚于钎缝,导致接头组织恶化,且剪切断裂以脆性断裂为主.综合考虑钎焊成本与接头强度使用要求,确定最佳钎焊工艺为590℃、30 min.     

三价铈离子掺杂氯化钾的光致发光性能

采用水热蒸发法制备了KCl∶Ce3+荧光粉。测量并分析了材料在室温下的真空紫外激发光谱及相应的发射光谱。结果表明激发谱显示6个峰,峰位分别为149、194、206、219、233和251nm。其中149nm的激发峰是基质吸收引起的;194、206、219、233和251nm是Ce3+离子的4f→5d跃迁引起的。发射峰显示双峰结构,峰位分别是311和326nm。此峰对应于Ce3+离子的5d→4f(2F5/2,2F7/2)跃迁。     

Effect of bonding variables on TLP bonding of oxide dispersion strengthened superalloy

Transient liquid phase (TLP) bonding has evolved as a successful alternative joining technique for high service temperature components (e.g., vanes and blades for aircraft gas turbine engines) made from superalloys when neither fusion welding nor solid-state bonding techniques are successful. However, study shows that the optimization of bonding variables is critical to achieve a metallurgically sound joint free from deleterious intermetallic constituents in the joint region. In this study, the influence of bonding pressure and interlayer thickness on microstructural developments at the joint region of TLP bonded oxide dispersion strengthened (ODS) superalloy MA758 was examined. A commercial interlayer based on the Ni–Cr–B (MBF-80) system was used and results showed that bonding pressure and interlayer thickness affected the final width of the joints. A theoretical study revealed that the TLP bonding time can also be reduced when there is an increase in bonding pressure.     

Cu/Al_2O_3复合薄膜的制备及其抗氧化性能

本文在纺织纤维基材表面采用二次溅射沉积法制备了Cu/Al_2O_3复合薄膜,利用扫描电镜(SEM)、X射线能谱仪(EDX)和矢量网络分析仪对室温环境下存放3600h的复合薄膜的表面形貌、元素含量以及屏蔽效能进行了测试,并与相同工艺条件下制备的纯Cu薄膜进行了对比分析。结果表明:与纯Cu薄膜结构的不稳定性相比,由于复合薄膜表层Al_2O_3薄膜的结构稳定性和致密性,Cu/Al_2O_3复合薄膜在保证高屏蔽性能的前提下,具有整体结构的稳定性,表现出了良好的抗氧化性能。     

Si3N4陶瓷/Nb/Cu/Ni/Inconel 600界面反应层形成机制研究

观察分析了Si3N4陶瓷/Nb/Cu/Ni/Inconel600界面处反应层的形貌、元素分布、反应层中的相结构、界面反应以及反应层的生长规律,研究了Si3N4陶瓷/Nb/Cu/Ni/Inconel600界面处反应层的形成机制.研究结果表明:在连接过程中,Cu层首先熔化,Nb、Ni向液态Cu中扩散溶解形成Cu-Nb-Ni合金,液态合金中的Nb和Ni向Si3N4表面扩散聚集并与Si3N4反应形成反应层;Si3N4侧的反应层主要物相是NbN和Nb、Ni的硅化物,Ni基合金侧反应相主要是NbNi3和Cu-Ni合金;在连接温度为1403 K的条件下,随着连接时间的增加,界面反应层厚度先快速增加,再缓慢增加.     

Transient liquid-phase bonding of ferritic oxide dispersion strengthened superalloy MA957 using a conventional nickel braze and a novel iron-base foil

It has been shown that an iron foil based on the Fe-B-Si system is a suitable material for use as a high-temperature interlayer for transient liquid-phase (TLP) bonding of ferritic oxide dispersion strengthened alloys. TLP bonding produced ferritic joints, free from intermetallic precipitates and identical in composition to that of the parent metal. In contrast, however, TLP bonding using the nickel-base foil, Bni1a, resulted in an austenitic bond region stabilized by the high nickel concentration. Furthermore, the retention of the melting point depressants, particularly silicon, at the centre of the joints resulted in the bond solidifying with the formation of silicide-boride precipitates both at the bond centre and at the braze/parent metal interface. High-temperature heat treatments failed to remove the -Fe phase and the precipitates, and their presence detrimentally affected the mechanical properties of the joint. The formation of intermetallic precipitates at the braze centre has been attributed to the initial high concentration of chromium present in the Bni1a brazing foil. Preliminary mechanical tests showed that bond strengths of joints made using the iron-base foil were superior to those obtained using the commercial nickel braze. When the iron-base foil was used, bond strengths both at room temperature and at the service temperature (700 °C) were near parent metal strengths. However, at room temperature, failure was observed to occur away from the bond interface, whilst at elevated temperatures, joints failed along the bond interface; this was attributed to the effects of melt-back phenomenon characteristic in TLP bonding.     

Brazing of WC–8Co cemented carbide to steel using Cu–Ni–Al alloys as filler metal: Microstructures and joint mechanical behavior

Three novel Cu–Ni–Al brazing filler alloys with Cu/Ni weight ratio of 4:1 and 2.5–10 wt% Al were developed and characterized, and the wetting of three Cu–Ni–Al alloys on WC–8 Co cemented carbide were investigated at 1190–1210?C by the sessile drop technique. Vacuum brazing of the WC–8 Co cemented carbide to SAE1045 steel using the three Cu–Ni–Al alloys as filler metal was further carried out based on the wetting test results. The interfacial interactions and joint mechanical behaviors involving microhardness, shear strength and fracture were analyzed and discussed. The experimental results show that all the three wetting systems present excellent wettability with final contact angles of less than 5?and fast spreading. An obvious degeneration layer with continuous thin strip forms in the cemented carbide adjacent to the Cu–Ni–Al/WC–8 Co interface. The variation of microhardness in the joint cross-section is closely related to the interactions(such as diffusion and solid solution) of WC–8 Co/Cu–Ni–Al/steel system. Compared with the other two brazed joints, the WC–8 Co/Cu–19 Ni–5 Al/steel brazed joint presents more reliable interlayer microstructure and mechanical property while brazing at the corresponding wetting temperatures for 5 min, and its average shear strength is over 200 MPa after further optimizing the brazing temperature and holding time. The joint shear fracture path passes along the degeneration layer, Cu–Ni–Al/WC–8 Co interface and brazing interlayer, showing a mixed ductile-brittle fracture.     

Counteracting particulate segregation during transient liquid-phase bonding of MMC-MMC and Al2O3-MMC joints

The microstructure and mechanical properties of MMC-MMC and Al2O3-MMC joints (MMC is metal matrix composite) produced at a bonding temperature of 853 K using copper foils ranging in thickness from 10 to 30 μm were examined. The particle segregation tendency during transient liquid-phase (TLP) bonding of aluminium-based MMC material markedly increases when the aluminium-based composite material contains large number of small radius (less than 10 μm) reinforcing particles. Also, the particle segregation tendency is much greater in dissimilar Al2O3-MMC joining since the rate of solid-liquid interface movement is much slower and the time required for completing the isothermal solidification during TLP bonding is much longer. The particle segregation tendency during MMC-MMC and Al2O3-MMC bonding can be counteracted using a combination of a short (1 min) holding time at the bonding temperature (853 K) and subsequent post-weld heat treatment at 773 K for 4 h. This TLP-bonding-heat-treatment cycle removes the retained eutectic phase present at the joint centreline. This revised version was published online in November 2006 with corrections to the Cover Date.     

Al-Cu双金属复合结构的扩散连接试验研究

应用扩散连方法进行了Al-Cu双金属复合结构的试验研究，比较了不同的焊接工艺，材料组合以及母材状态情况Al合金与Cu的连接性，观察了接头区域的微观组织结构，研究表明，固相扩散连接是一种适用于异种材料连接的有效方法，通过在连接区域形成Al-Cu金属间化合物，达到Al和Cu的有效连接，材料组合，母材原始状态以及连接工艺参数对Al合金与Cu的扩散连接存在着明显的影响。表面镀Ni工艺不但能够有效阻止Al和Cu之间形成脆性相，而且Al和Ni之间形成了良好的扩散连接，改善了接头性能。     

Mechanochemical joining in cold roll-cladding of tri-layered Cu/Al/Cu composite and the interface cracking behavior

The nature of interface bonding in tri-layered Cu/Al/Cu clad-composite processed by cold roll-bonding was examined by fracture surface analyses. The peeled-off fracture surface of Cu side revealed polygon-shaped intermetallic region, Al islands with the central ridge-like pattern and valley-trail like Cu network. The area fraction of region with intermetallics, region with mechanical metallic bonding and unbonded/weakly bonded region was observed to be 0.148, 0.596 and 0.256 respectively. The mechanochemical bonding through pressure- and heat-induced intemetallic formation was found to be important in joining Cu and Al even in cold-roll-bonding in addition to typical mechanical joining. Cu/Al metallic joint interface was strong enough to induce the crack to propagate through the softer Al matrix adjacent to the mechanically joined interface and along the intermetallic layer.     

Effect of Ni interlayer on characteristics of diffusion bonded Mg/Al joints

Magnesium and aluminium were joined through diffusing bonding with a Ni interlayer prepared by plasma spraying for the first time. Examination of the microstructure and phase constitution of interfacial regions indicated that Mg–Al reaction was successfully prevented in the presence of the Ni interlayer. With the elevation of temperature, a reaction layer of Mg₂Ni intermetallic was formed at Mg/Ni interface but few Al–Ni intermetallic was generated at Al/Ni interface. The mechanical test results showed that the tensile strength of the Mg/Al joint was substantially improved compared to that of the direct joint of Mg and Al. A maximum value of 5.8?MPa was obtained at 420°C for the joint with Ni interlayer.     

高体积比SiCp/A356复合材料真空扩散钎焊接头组织与性能研究

采用快速甩带技术制备了7组(Al-33.3Cu-6.0Mg)-xNi(x=0,0.5,1.0,2.0,3.0,4.0,5.0,质量分数/%)急冷箔状钎料,分别对化学镀Ni-P合金前后的SiCp/A356复合材料进行真空扩散钎焊。通过剪切实验对钎焊接头的抗剪强度进行测定,并利用扫描电镜和能谱分析等方法对接头微观组织进行观察和分析。结果表明,当向Al-33.3Cu-6.0Mg钎料合金中添加不同含量的Ni时,其急冷钎料的固-液相线(504~522℃)变化较小;当w(Ni)=3%且在570℃、保温30min的钎焊工艺下,A356基体/钎料两界面间发生适当的互扩散和溶解现象(585℃时出现溶蚀缺欠),且部分钎料/SiC颗粒的接触界面发生Mg参与的化学反应,接头抗剪强度达到64.97 MPa;而在同种钎焊工艺下,对于化学镀Ni-P合金镀层后的SiCp/A356复合材料,其接头处A356基体/Ni-P合金镀层/钎料等接触界面易于形成富含Al、Ni的致密反应层,接头连接质量显著提高,且w(Ni)=4%时,接头抗剪强度达到79.96 MPa。     

Diffusion Bonding of Ti-6Al-4V to QAl 10-3-1.5 with Ni/Cu Interlayers

Ti-6Al-4V and QAl 10-3-1.5 diffusion bonding has been carried out with Ni/Cu interlayers. The diffusion-bonded joints are evaluated by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and microhardness test. Intermetallic compounds at the interface zone are detected by X-ray diffraction (XRD). Interfacial microstructure of TiNi+CuTis+α-Ti forms at the Ni/Ti-6Al-4V transition zone and Cu (ss. Ni) solid solution forms between Ni/Cu interlayers. The thickness of reaction layer (TiNi) increases with bonding time by a parabolic law: y2=K0exp(-150000/RT)t, and K0=2.9×10~7 m2/s is figured out from the experiment data.     

SiCp/Al复合材料焊接综述

为实现SiCp/Al复合材料的高质量可靠焊接,推广SiCp/Al复合材料在各领域的应用,调研了国内外SiCp/Al复合材料不同焊接方法的研究现状。在熔化焊方面,国内外学者通过调整工艺参数、在焊缝中加入Ti元素发生诱发反应等方法,抑制了焊缝中Al4C3针状脆性相的形成,从而提高了焊接接头的力学性能。在搅拌摩擦焊方面,国内外学者针对不同材料设计了专用的焊接搅拌头,以保证它们具备高耐磨性与足够的冲击韧性,在焊接过程中不出现破损情况;关注了焊接过程中焊接头转速、焊接速度、轴向力与热输入等因素,以获得力学性能优秀、晶粒细小均匀的焊接接头。在扩散焊方面,国内外学者探究了中间夹层对焊缝界面间原子相互扩散的促进作用;采取不同工艺参数,以外加超声或电子束表面加热等方式促进了原子间的相互扩散,以获得力学性能优异的焊接接头,提高焊接效率。在钎焊方面,国内外学者通过探究钎料与SiCp/Al复合材料之间的润湿性来组合钎料与钎剂,通过化学腐蚀处理表面暴露颗粒增强相、在复合材料表面电镀金属等方法来增大钎料与增强相的润湿性、解决钎料铺展受阻的问题,以进一步提高钎焊焊接接头质量。     

Microstructural Evaluation of 410 SS/Cu Diffusion-Bonded Joint

In the present study, a grade of stainless steel (SS, 410) and copper plates were joined through diffusion bonding by using a nickel interlayer at temperature range of 800-950℃. These were performed through pressing the specimens under a pressure of 12 MPa for 60 min under 1.33×10 -2 Pa (10-4 torr) vacuum. The microstructure and phase constitution near the diffusion bonding interface of Cu/Ni and Ni/SS were studied by optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and a...