The Improvement of Oxidation Resistance of a Re-Based Diffusion Barrier/Ni–Al Coating on the Single-Crystal Ni-Based TMS-82+ Superalloy

摘要

Oxidation behavior of a Re-based diffusion barrier/Ni–Al coated single-crystal (SC) Ni-based TMS-82+ superalloy was studied to compare with those of the base and Ni–Al coated superalloys under cyclic air at 1150 °C for 200 h. The base superalloy showed a negative mass gain due to extensive oxide spallation, and the Ni–Al coated superalloy without the diffusion barrier started to spall slightly after about 90 h. The oxidation resistance of the Ni–Al coated superalloy with the Re-based diffusion barrier was greatly improved due to the formation of a dense ?-Al2O3 layer in the scale. The Re-based alloy was an effective diffusion barrier layer against inward diffusion of Al and outward diffusion of alloying elements in the alloy substrate due to the reduced thickness of interdiffusion zone with small amount of detrimental precipitates and higher content of Al in the Ni–Al coating that supplied enough Al for formation of the ?-Al2O3 layer.