Effect of heat treatment on microstructure and high temperature properties of IC10 superalloy TLP diffusion welding under 80 μm gap

The IC10 superalloy with 80 μm gap was welded by TLP diffusion welding. The microstructure, morphology, modulus of elasticity, microhardness, high temperature tensile strength, high temperature durability and fracture morphology before and after heat treatment of IC10 joints were tested by using scanning electron microscopy (SEM/EDS), nano-indenter and high-temperature tensile testing machine. The results showed that when SBM-3 was used as the intermediate solder and the gap size of the weld was 80 μm, under the welding process conditions of 1 250 ℃, 5 MPa, and 6 h, the morphology and base composition of the weld seam and the base metal were similar. After heat treatment, the tensile strength was 268 MPa, which higher than 97.5% of base metal (275 MPa) at the test temperature of 1 100 ℃. The high temperature durability of the IC10 joints were tested, the creep time of the joints was more than 117 h under the condition of the temperature of 1 100 ℃ and the stress of 36 MPa, which was higher than 90% of the base material. In the joint structure, a larger volume of γ + γ′ phase existed in the weld, and the joint structure transitioned smoothly from the base material to the welded joints. In high-temperature tensile and high-temperature durability tests, cracks started to expand from at the edge of the borides and carbides as well as the edge of the γ + γ′ eutectic. Heat treatment increased the elastic modulus of the base material while reduced the elastic modulus of the weld. The reduction of the joint elastic modulus improves the high-temperature mechanical strength of the TLP diffusion welded joints.