Microstructures and properties of transient liquid phase diffusion bonded joints of DD3 single crystal superalloy

The microstructures and the stress-rupture properties of TLP diffusion bonded joints of DD3, a nickel-based single crystal superalloy, were investigated. Two interlayer alloys developed for DD3 were employed: D1P, a powder alloy, and D1F, an amorphous foil. The results show that there exists obvious microstructural inhomogeneity in the joint diffusion bonded with D1P, and it requires a long time diffusion under high temperature to eliminate this inhomogeneity. However, when the DD3 alloy was bonded with the amorphous foil interlayer alloy, D1F, it was easier to obtain the joint microstructure identical to that of the base metal. Under proper bonding condition, the stress-rupture property at 980°C of the diffusion bonded DD3 alloy joints reached or surpassed 90% of that of the base metal.