The Improvement of Oxidation Resistance of a Re-Based Diffusion Barrier/Ni–Al Coating on the Single-Crystal Ni-Based TMS-82+ Superalloy
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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 α-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 α-Al2O3 layer.
KeywordsSingle-crystal Ni-based superalloy Diffusion barrier Coating Oxidation Microstructure Electron probe microanalysis (EPMA)
This work was financially supported by The Program for Professor of Special Appointment (Eastern Scholar) at Shanghai Institutions of Higher Learning, China (No. DF2009-01), and Innovation Program of Shanghai Municipal Education Commission, China (No. 10ZZ126). This work described in this paper was also partly supported by the Program for New Century Excellent Talents (NCET-07-0162) in University, Ministry of Education, P.R. China, and by the Fundamental Research Funds for the Central Universities of China under Grant No. N090505001. Sincere thanks also go to Prof. T. Narita for useful discussion on the present work.
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