Microstructure and property of Ni3Al-based superalloy IC10 brazed joint

Abstract

For Ni3Al-based superalloy IC10 turbine blades， some defects， such as cracks and ablations， would appear after long-term service. To shorten the overhaul period， the turbine blades can be repaired using the brazing technology. In this study， an independently designed Co-based filler alloy （CoCrNi（W，Al，Ti，Mo，Ta）-B） was used to join the IC10 superalloy. The effects of the brazing gap and the brazing time on the joint microstructure and mechanical properties were investigated. The results show that the designed filler alloy has good brazeability at 1220 ℃ for IC10 superalloy. Because of the interreaction and mutual diffusion， the brazing seam is wider than the preset gap. Meanwhile， the matrix of brazing seam is γ＋γ′ dual phase which was similar to the IC10 base material. Because of the boron in the filler alloy， a large number of white borides are formed. The brazing holding time has little influence on the microstructure and strength of the joint， but the brazing seam has significant effect.With the brazing seam wider， the joint strength tested at 1000 ℃ increases gradually. When the brazing seam is set at 0.15 mm， the joint strength is 454 MPa， which is close to that of the IC10 base material. According to the joint fracture morphology， the increase in joint strength is mainly due to the small and diffuse white boride phase in the joint， inducing the tortuous crack propagation path.

Keywords

• ic10 superalloy
• brazing seam
• joint microstructure
• high-temperature strength