Abstract
The present work investigates the high temperature oxidation and corrosion behaviour of high entropy superalloys (HESA). A high content of various solutes in HESA leads to formation of complex oxides, however the Cr and Al activities of HESA are sufficient to promote protective chromia or alumina formation on the surface. By comparing the oxidation and corrosion resistances of a Ni-based superalloy—CM247LC, Al2O3-forming HESA can possess comparable oxidation resistance at 1100 °C, and Cr2O3-forming HESA can exhibit superior resistance against hot corrosion at 900 °C. This work has demonstrated the potential of HESA to maintain surface stability in oxidizing and corrosive environments.
Highlights
Many gas turbine engine components are made of Ni-based superalloys, and the continuing strive to improve the engine efficiency has demanded improved temperature capability in these materials.As a result, high levels of refractory elements have been added to Ni-based superalloys to improve their high temperature strength [1,2,3,4,5]
Novel high temperature alloys based on the “high entropy alloy” concept have been designed by incorporating both sluggish diffusion and lattice distortion strengthening effects [15,16,17,18], and these materials have been referred to as “high entropy superalloys” (HESAs) [19]; this alloy design approach allows HESAs to be strengthened by high contents of various solutes rather than alloying with a high content of refractory elements
HESAs possess similar microstructures to those of Ni-based superalloys, which is thermodynamically stable FCC γ and L12 γ1, and our previous study has shown that HESAs can exhibit higher hardness at elevated temperature than conventional Ni-based superalloys
Summary
High levels of refractory elements have been added to Ni-based superalloys to improve their high temperature strength [1,2,3,4,5]. This has led to high alloy density and a high propensity to form refractory oxides that degrade the surface stability [6,7,8,9,10]. The aim of present work was to investigate the high
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