Abstract
TiAl-Nb based alloys have great application potential in high temperature components of advanced aircrafts and weapons due to excellent overall performance. However, high-temperature oxidation resistance of these alloys could not meet requirements of actual service. Research progress on high-temperature antioxidation protection of TiAl-Nb based alloys was reviewed, covering multi-alloying, surface alloying, oxidation resistant coatings and high-temperature antioxidation mechanisms. Meanwhile, characteristics of different oxidation protection measures were analyzed, and development trend of high-temperature antioxidation protection of TiAl-Nb based alloys were prospected. Domestic and foreign studies showed that multi-alloying was an effective way to promote the high-temperature oxidation resistance of TiAl-Nb based alloys by improving microstructures and/or promoting formation of protective Al2O3 scale while suppressing formation of TiO2 during oxidation. Surface alloying could significantly promote oxidation resistance of TiAl-Nb based alloys by improving microstructures and constituents of alloy surface, and promoting formation of Al2O3 or SiO2 protective films during oxidation. However, inter-diffusion of Al, Si and Ti etc. between alloying layer and the substrates would exacerbate degradation of the alloying layer. Surface multi-alloying especially addition of minor reactive elements had good effects on promoting formation of protective oxide films and suppressing inter-diffusion. Preparing oxidation resistant coatings which formed protective oxide film and suppressed internal diffusion of O during oxidation was also an effective way to achieve excellent high-temperature oxidation resistance of the alloys. However, poor bonding strength and reaction-diffusion between the coatings and substrates should be solved carefully, and preparing composite coatings or diffusion impervious layers is proved to be effective in resolving above problems.
Key words
TiAl-Nb based alloy; alloying; surface alloying; high-temperature oxidation resistant coatings; antioxidation mechanisms
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JIA Ping-ping.
High-temperature Antioxidation of TiAl-Nb Based Alloys[J]. Surface Technology. 2018, 47(3): 224-230
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Funding
Supported by the Shaanxi Military and Civilian Integration Project (16JMR04) and the Key Research Project of Weinan Normal University (17YKF05)