Influence of the Substrate Orientation on the Isothermal Solidification during TLP Bonding Single Crystal Superalloys

Angle deviations between the two substrates during transient liquid phase （TLP） bonding single crystal superalloys cannot be avoided. In the present work, specimens have been prepared to investigate the influences of the various substrate orientations. It is found that the width of the non-isothermal solidification zone （NSZ） is linear with the square root of the isothermal solidification time. This suggests that the isothermal solidification process is B-diffusion controlled in different substrate orientation deviations. And also the width of the NSZ increases with increasing angle deviation, indicating that the isothermal solidification time needed in the TLP bonding increases with increasing orientation deviation between the two substrates.

Thermal Properties of Ni–Cr–Si–B–Fe Based Interlayer Material and Its Application in TLP Bonding of IN 718 Superalloy

A new Ni–Cr–Si–B–Fe fi ller material is prepared for transient liquid-phase(TLP)bonding of Inconel 718 superalloy by mechanical alloying technique.The melting temperature range of the fi ller material and its activation energy of melting are determined by diff erential scanning calorimetry technique.The activation energy and melting temperature of the alloy powder decrease with increasing milling time.Inconel 718 alloy was joined via TLP by using the newly developed fi ller material.The eff ect of TLP bonding temperature and time on microstructural evolution and mechanical properties of the joint was investigated.Three distinct microstructural regions were observed in the bonding area:isothermal solidifi cation zone consisting of a single-phase solid solution,diff usion aff ected zone consisting of extensive diff usion-induced precipitates of metallic boride,and unaff ected base material.The ultimate shear strength and microhardness of the TLP-bonded joint increase with bonding time and temperature.

Transient liquid phase diffusion bonding of a single crystal superalloy DD6

DD6 alloy was bonded by transient liquid phase (TLP) diffusion bonding. The main compositions of the interlayer alloy employed were similar to those of the base metal, DD6, and a certain amount of element B was added as the melting point depressant. The results show that it is difficult to obtain the joints with the microstructures completely homogeneous. For the joint TLP diffusion bonded at 1290℃ for 12h, about half areas of the beam possessed a γ+γ′ microstructure, nearly identical with that of the base metal, and the other local areas consisted of γ-solution, borides, etc. Prolonging the bonding time to 24h, the inhomogeneous areas in the joint reduced, and the joint property improved. The joint stress-rupture strength at 980℃ and 1100℃ reached 90%-100% and 70%-80% of those of the base metal respectively.

Improvement of Joint Strength of SiCp/Al Metal Matrix Composite in Transient Liquid Phase Bonding Using Cu/Ni/Cu Film Interlayer

The compact oxide on the surface of SiCp/Al metal matrix composite （SiCp/Al MMC） greatly depends on the property of the joint. Inlaid sputtering target was applied to etch the oxide completely on the bonding surface of SiCp/Al MMC by plasma erosion. Cu/Ni/Cu film of 5μm in thickness was prepared by magnetron sputtering method on the clean bonding surface in the same vacuum chamber, which was acted as an interlayer in transient liquid phase （TLP） bonding process. Compared with the same thickness of single Cu foil and Ni foil interlayer, the shear strength of 200 MPa was obtained using Cu/Ni/Cu film interlayer during TLP bonding, which was 89.7% that of base metal. In addition, homogenization of the bonding region and no particle segregation in interfacial region were found by analysis of the joint microstructure. Scanning electron microscopy （SEM） was used to observe the micrograph of the joint interface. The result shows that a homogenous microstructure of joint was achieved, which is similar with that of based metal.

Microstructures and properties of transient liquid phase diffusion bonded joints of Ni_3Al-base superalloy

An investigation of transient liquid phase (TLP) diffusion bonding of a Ni 3Al base directionally solidified superalloy, IC6 alloy, was presented. The interlayer alloy employed was Ni Mo Cr B powder alloy. The results show that the microstructure of the TLP diffusion bonded joints is a combination of γ solid solution (or a γ+γ′ structure) and borides. With the bonding time increasing, the quantity of the borides both in bonding seam and adjacent zones is gradually reduced, and the joint stress rupture property is improved. The obtained stress rupture property of the TLP bonded joints is on a level with the transverse property of IC6 base materials. [

Microstructural Evolution of a Ni-base Alloy DZ468 Joint Bonded with a New Co-base Filler

Ni-base alloy DZ468 has been joined by transient liquid phase bonding technique with a newly developed Co-based filler. The microstructures of the Co-base filler and the joint, the effects of heat treatment on microstructure and hardness of the joint have been investigated by various experimental methods. Results show that the Co-base filler consists of γ, M2B, M5B3 and M23B6 phases. Because of the interdiffusion between the base metal and the filler, γ, MC, M5B3 and M23B6 phases are formed in the bonding zone. And localized liquidation of substrate occurs in the diffusion affected zone, with MC and M3B2 precipitating in this area. During heat treatment, the volume of the intermetallic phases in the bonding zone resulting from incomplete isothermal solidification decreases obviously. On the contrary, the width of the diffusion affected zone increases at the solution stage and subsequently decreases at the aging stages.