Interfacial microstructure and properties of TiC cermet and GH3128 joint brazed using AgCuNiLi

Abstract:

TiC cermet and GH3128 nickel-based superalloy was brazed using AgCuNiLi filler alloy. The results show that the interfacial microstructure of the joint brazed at 840°C for 10min is TiC cermet/(Cu,Ni)/Ag(s.s)+Cu(s.s)/(Cu,Ni)/GH3128. With the increase of temperature and holding time, the (Cu,Ni) solid solution at the TiC cermet side thickens and grows in the form of dendrite crystal; besides, the eutectic microstructure in the brazing alloy decreases. The analysis on the interfacial microstructure shows that the addition of Li in the alloy promotes the forming of the (Cu,Ni) solid solution. However, the continuing growth of the (Cu,Ni) solid solution is controlled by diffusion of the Cu element in the brazing alloy. Shear strength of the joint increases gradually and then decreases slowly with the increase of the brazing temperature. The highest shear strength of 204MPa was obtained when the specimens were brazed at 880°C for 10min.