Recrystallization on Interface between NiCoCrAlYTa Coating and Nickel-Based Super-Alloy

Abstract:

The NiCoCrAlYTa coating was prepared on Ni-based single crystal super-alloys by low pressure plasma spraying (LPPS). The influences of heat treatment and pre-peening on the interface recrystallization of NiCoCrAlYTa coating and nickel-based super-alloy substrate were investigated by X-ray, SEM, BES and EPXMA. It was found that cellular recrystallization occurred at the diffusion area of samples adopting the vacuum heat treatment at the temperature of 1080 ℃, while no recrystallization appeared at the temperatures of 1000 ℃ and 850 ℃. Recrystallization was also observed in the sample subjected by pre-peening with more than 0.2 MPa, followed by 1080 ℃, 6 h heat treatment and 850 ℃, 24 h aging treatment, while no recrystallization was observed in the sample subjected by no pre-peening followed by above mentioned heat treatment. The results revealed that element Ta aggregated within cellular grains and that inter-diffusion took place and Ta-rich phases (Ni2Ta, Cr2Ta) were formed at the interface through heat treatment

Key words:heat treatment; peening; NiCoCrAlYTa coating; Ni-based single crystal super-alloys; recrystallization