Papers by Keyword: Transient Liquid Phase (TLP) Bonding

Abstract: This paper presents the use of the transient liquid phase concept to grow the high temperature Cu₆Sn₅ intermetallic compound between Cu₃Sn-rich powdered alloys and molten Sn. In this study, high temperature powdered alloys containing high fractions of Cu₃Sn were fabricated from a chill-cast Sn-60 wt.%Cu alloy. A ternary alloy with composition of Sn-59 wt.%Cu-1 wt.%Ni was also prepared to investigate the effect of Ni. The reaction products were obtained at 250°C over a period of 30 minutes. The results provide new insight into the mechanism of the interfacial reaction between liquid Sn and solid Cu₃Sn-rich alloy with and without Ni additions.

Abstract: Transient liquid-phase(TLP) bonding of SiC particle reinforced aluminum matrix composite(SiCp/Al MMCs) ,using Cu film, Cu foil, Ni foil and Cu/Ni/Cu multilayer foil interlayer, was investigated. The effect of surface status, interlayer species and bolding time on bonding microstructure and properties were also estimated by metallographic microscope, scanning electron microscopy (SEM), X ray diffraction and tensile testing machine. The results show that adding holding time can improve shear strength of joint. Better strength of joint can be obtained due to without the effect of oxide with Cu film as interlayer, when bonding at 853K for 120min under 2MPa pressure, the shear strength of bonded joints can obtain 169.1MPa, about 81.7 percentage of the strength of base material. Best strength of joint can be obtained with Cu/Ni/Cu multilayer foil as interlayer, when bonding at 923K for 120min under 2MPa pressure, the of bonded joints can obtain 189.6MPa, about 84.6 percentage of the strength of base material.

Abstract: An aluminum base interlayer was used for transient liquid phase bonding of pure aluminum under argon flux. The bonding was carried out at 595°C for 2 minutes under 7MPa. Microstructure of the joint was studied with SEM and EDX, and the mechanical properties were analyzed by tensile test and bending test. A homogenous bonding zone is observed in the joint. The defects in the joint are silicon oxides and voids. The tensile strength of the joint is 190MPa, and no failure occurs when the joint is bent to 180°. This indicates that TLP bonding can produce a strong and ductile Aluminum joint, which is equivalent to the base metal.

Abstract: The key to accomplish transient liquid phase bonding in the atmosphere is to control bonding temperature, holding time and compressive pressure. The measurement and control system was independently developed based on an industrial computer and I/O cards. The output of a medium frequency power supply and the opening degree of a proportional relief valve were regulated to control bonding temperature and compressive pressure. Improved PID algorithm was presented, and the temperature precision in steady stage reached ± 0.1%. The system is applied to TLP bond steel pipes successfully.

Abstract: T91/12Cr2MoWVTiB was bonded by transient liquid phase bonding process with different pressures, one commercial FeNiCrSiB was used as the interlayer. The microstructure and components distribution of the bonded joints were examined by optical microscope and scanning electron microscopic techniques. Furthermore, the properties of the joints were also tested. The results indicate that with the increase of the pressure – from 2 MPa to 6 MPa – the microstructures and mechanical properties were improved, and more similar to those base alloys. A theoretical study also revealed that the isothermal solidification complication time can be shorter, because the maximum liquid width was reduced with the existence of pressure.

Abstract: Transient liquid-phase (TLP) bonding of aluminium-based metal matrix composite (MMC) has been investigated. An attempt was made of using an Ag/Cu /Ag film as an interlayer for bonding to improve the joint strength. The oxide on the surface of SiCp/Al MMC was etched completely by plasma. Ag/Cu/Ag film of 8µm thickness was prepared by magnetron sputtering method on the clean bonding surface in the same vacuum chamber. Compared with the same thickness of single Cu foil and Ni foil interlayer, which are widely used for joining SiCp/Al MMC material, the shear strength of 192.8MPa was obtained, which was 86.5% that of base metal. Discussion was made on the bonding process and microstructure.

Abstract: 2D Fiber Reinforced carbon-carbon composites (C/C) was successfully bonded to itself with Ti-Ni-Ti sandwich interlayer by transient liquid phase bonding at 1050°C for 20~100 min under axial pressure of 0.1 MPa. The microstructures of joints were investigated and bonding strengths were examined, fracture surfaces were characterized by SEM and XRD. The results show that Ti-Ni eutectic liquid infiltrates into the interconnected capillaries of C/C through the open pores of the C/C boding surface. The presents of the breakpoints in joint alloy and the reaction between Ti and C are beneficial to the improvement of bonding strength. The shear strength of joint is as high as 37.4 MPa.

Abstract: The bond interface of a TLP (Transient Liquid Phase) bonded tin has been observed with a TEM to investigate the effect of the liquid phase on the behavior of the superficial oxide film at the interface during the bonding process. In the solid-state-diffusion bonded joint without filler, abundant oxide inclusions were observed to be distributed within a region of a few 100 nm widths along the bond interface. In comparison with this, the liquid phase introduced by the eutectic reaction of the bismuth filler with the tin substrate decreased the width of the interfacial region involving abundant oxide inclusions to form a rather layer structure a few 100 nm thick consisting mainly of SnO2. It also enhanced the annihilation of the uncontacted areas at the interface. The layer of the oxide became discontinuous and coalesced with an increase in bonding temperature and pressure, and areas where no oxide inclusion could be observed at the interface were increased, when the liquid phase was formed. Owing to these effects, the bond strength rose at lower bonding temperatures and pressures when the bismuth filler was applied.

Abstract: Transient Liquid Phase Bonding (TLPB) is a joining process that uses liquid as medium for the establishment of an interface between two faying surfaces. In TLPB, as opposed to brazing process, the careful selection of the interlayer materials and the use of a prolonged heat treatment, allows for isothermal solidification and results in interfaces possessing potential service temperature higher than the joining temperature itself. Such a process is attractive for joining ceramics to metals and composites. In this presentation, the applicability of TLPB for various systems: Si3N4/FA-129 iron aluminide alloy, Al2O3/Al2O3, Al-Al2O3/Al-Al2O3, Al-Al2O3/Al-SiC and Al-Al2O3/Al. Results on the interface formation, interfacial microstructure and mechanical properties will be presented. A comparison of the TLPB joint properties with traditional joining for similar systems will be illustrated.

Abstract: The effect of a mixed powder on the wide gap transient liquid phase diffusion bonding of a directionally solidified Ni base superalloy, GTD-111 was investigated. The mixed powder consisted of a mixture of a powdered Ni base filler (GNi-3) and powdered base metal (GTD-111). The range of the base metal powder was 40 to 70wt%. Bonding was performed at a temperature of 1463K, using various holding time. In the case of a lower 50wt%, the base metal powders completely melted and base metal mating at the interface dissolved at an early time, and extent of dissolution of base metal decreased with increasing mixing ratio. Liquid was eliminated by isothermal solidification, which was controlled by the diffusion of B into the base metal. The solids in the bonded interlayer grew epitaxially from the mating base metal inward from the insert metal and the number of grain boundaries formed at the bonded interlayer corresponded with those of the base metal. The finishing time for isothermal solidification was about 74ks. In the case 60wt% and higher, the base metal powders partially melted and remained in the vicinity of bonded interlayer. The solid was formed from the remaining powder and base metal mating at the interface. Finally, the bonded interlayer underwent the poly-crystallization when isothermal solidification was complete. The contents of Al and Ti in the bonded interlayer with a holding of 74ks were equal to that of the base metal.