Effect of bonding temperature on microstructure development during TLP bonding of a nickel base superalloy

The effect of bonding temperature on microstructure of a transient liquid phase (TLP)-bonded GTD-111 nickel base superalloy, using a Ni–Si–B interlayer, was investigated. At low bonding temperatures microstructure of the joint centerline is controlled by B diffusion. However, at high bonding temperature effect of base metal alloying elements on the joint microstructure development was more pronounced. Effects of bonding temperature on the formation of secondary precipitates in diffusion-affected zone and isothermal solidification time were also analyzed. It was found that above a critical temperature, formation of borides in diffusion-affected zone is suppressed and the time required for isothermal solidification completion is increased.