Microstructure analysis of TLP bonded joint of GH99 alloy

GH99 alloys were joined by transient liquid phase (TLP) process using self-designed Ni-Cr-Si-B interlayers. The effects of joining parameters and interlayer components on the interfacial microstructure of the joints were investigated with SEM and EDS. The results showed that with the increase of holding time and temperature, the precipitation of the compounds reduced and the microstructure of the joints became more uniform. The precipitation of the compounds in the joints was related to the diffusion of the melting point depressants. B element in the interlayer was one of the melting point depressants, and its content directly affected the quantity of the compounds in the joints. Because Si element in the base alloy was highly solid dissolved, the Si-rich compounds were reluctant to precipitate during bonding.