DIFFUSION BRAZING OF A NICKEL BASED SUPERALLOY PART 2 - EFFECT OF SOLIDIFICATION MODE ON THE MECHANCIAL PROPERTIES

Relationship between microstructure and mechanical properties of transient liquid phase (TLP) bonded joints of GTD-111 nickel base superalloy using a Ni-Si-B interlayer was investigated. Shear strength and hardness profile of the joints were discussed with respect to the bond microstructure. In the bonding condition, in which isothermal solidification has not been completely accomplished, eutectic constituent which has the highest hardness in the bond region is the preferential failure source. There is an inverse relation between the eutectic size and shear strength of the joints. At the bonding time of 75 min at 1100 degrees C, when the eutectic products are completely removed, bonds with shear strength of about 68% of that of the base metal are achieved.