Effect of filler metal chemical composition on the TiAl/IN738 dissimilar brazed joint
Dariush Kokabi, Ali Kaflou, H. R. Rastifard
Abstract
This paper investigates the microstructure and mechanical properties of dissimilar brazing of γ-TiAl/IN738 superalloy using two different filler metals. The microstructure of the two joints was comprised by the continuous intermetallic layers formed during holding time at the bonding temperature, and even during cooling. It was observed that the presence of the thick continuous brittle phases in the bond region of the IN738/Cu/TiAl joint led to lower mechanical properties in comparison with the IN738/Ni–Si–B/TiAl joint. The fracture occurred in the Reaction Layer(RL)/TiAl interface and the RL/Solidified zone(SZ) interface of the joints using Ni–Si–B and Cu filler metals, respectively. Also, the joint made using Ni–Si–B filler metal exhibited higher shear strength compared to the joint made using Cu filler metal by 20%.