High Temperature Properties Of Advanced Directionally-Solidified High Entropy Superalloys

High-Entropy-Superalloys (HESA) with good cost-performance has been proposed. In present work, the high temperature phase stability, oxidation, hot corrosion and mechanical properties of HESA alloys were studied. The microstructure of HESA is composed of stable FCC gamma matrix and L1(2) gamma ' precipitates, and both gamma and gamma ' phases are highly alloyed. This gamma / gamma ' microstructure can remain stable after long term exposure at inter-mediate to high temperatures. With respect to surface stability, HESAs show high Al and Cr activities to form either protective Al2O3 or Cr2O3 rapidly. With minor additions of refractory elements, the high temperature hardness of HESA can be higher than that of conventional superalloy. HESAs show comparable tensile strength and creep rupture properties comparing to that of commercial superalloys. Furthermore, their densities are below 8.0 g.cm(3), and the cost of raw materials can be 20 % cheaper than that of CM247LC. Therefore, the potential of HESAs for high temperature applications are revealed in present article.