EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

Refractory high entropy alloys (RHEAs) present a new class of metallic alloys with promising high-temperature properties. These alloys are mainly based on single-phase bcc or ordered B2 solid solution and can contain different secondary phases. However, secondary phases in RHEAs usually precipitate in an uncontrolled manner deteriorating room-temperature ductility abruptly. Thus, there is a need to develop precipitation-hardenable RHEAs with balanced mechanical properties. In this study, we proposed new non-equiatomic RHEAs composed of Ti, Nb, Hf, Al, and Ta. The experimental alloys were fabricated by vacuum arc melting. It is revealed that after annealing at 1200°C for 24 hours, the alloys had a single-phase microstructure and substantial ductility at room temperature. Further annealing at 600°C for 24 hours resulted in precipitation of the Widmanstatten orthorhombic particles embedded into the B2 matrix. Annealing at 600°C was found to substantially increase the strength of certain alloys at room and elevated temperatures while maintaining sufficient room temperature ductility. The composition-structure-property relationships and possibilities for further improvements in properties are discussed.
This study was supported by Russian Science Foundation, grant № 19-79-30066