Transient liquid phase metallic bonding of an inconel 718SPF superalloy

The applicability of the transient liquid phase (TLP) metallic bonding method for joining fine-grained Inconel 718SPF(R) superalloy sheers by inserting a Ni-P or a Ni-Cr-P amorphous interlayer has been evaluated. The results show that a joint with uniform chemical composition could be obtained for the Inconel 718SPF superalloy with a Ni-P interlayer at 1100 degrees C for 8 h. When a Ni-Cr-P inter- layer was used under the same metallic bonding conditions, the concentrations of nickel, iron and niobium in the bond region and in the base metal had a difference of more than 2 wt-%. This means that longer bonding time was required to homogenize the chemical compositions of bonds with a Ni-Cr-P interlayer The joints with a Ni-P interlayer showed higher bond strength than did those with a Ni-Cr-P interlayer. Furthermore, many grain boundary precipitates were found.