The Effect of Transient Liquid Phase Bonding Temperature on Microstructural Characteristics of Hastelloy X Superalloy Joints
The effect of Transient liquid phase (TLP) bonding temperature on microstructural characteristics of Hastelloy X superalloy joints with BNi-2 filler metal was investigated. TLP process at 1055, 1115 and 1175oC for 45 minutes of bonding time in a vacuum furnace at a pressure of 1.33 x10-3 pa by BNi2 filler metal was done. At 1055 oC the eutectic phases was formed in the centre of the joining zone, which consists of Mo and Cr-rich boried and nickel silicate. By increasing the temperature to 1115 oC , the diffusion rate of the melting point depressants (MPD) elements from the liquid layer side to the base metal was increased and the width of eutectic phase was decreased. Also, the isothermal solidification zone (ISZ) was completed in 1175 oC . By increasing temperature to 1175 oC, the hardness of ISZ was increased, but the hardness of the diffusion affected zone (DAZ) was decreased.
Keywords- Hastelloy X, BNi-2, temperature, melting point depressants, Isothermal solidification Zone.