The inhibiting effect of Re-rich layer on the interdiffusion between NiAl and Ni3Al-based superalloy and its degradation

Abstract

A NiAl alloy/ Ni3Al-based superalloy diffusion couple with an electroplated NiRe layer was prepared. High-temperature interdiffusion performance of the diffusion couple was analyzed at 1100 ℃ under argon atmosphere and compared with that of the blank group without NiRe layer. A Re-based diffusion barrier formed during the diffusion. The microstructural instability of the superalloy was found to be alleviated by the Re-based diffusion barrier, and the detailed microstructure of the diffusion barrier was identified to be Re-rich σ phases and Mo-rich α phase detected by TEM. The chemical diffusion coefficient of Al was reduced by about two orders of magnitude with the modification of the Re-based diffusion barrier. A microstructural degradation of the Re-based barrier layer was observed after high-temperature diffusion of 300 h, which can be attributed to the internal diffusion of Mo.