Development of a Ti30Hf20Nb20Ta10V10Mo7W3 refractory high entropy alloy with excellent mechanical properties and wear resistance

Abstract

Refractory high entropy alloys (RHEAs) have attracted a great deal of attention for the competitive properties at elevated temperatures, whereas the ambient-temperature brittleness has been still a bottleneck for practical applications. Herein, we report on a newly-designed Ti30Hf20Nb20Ta10V10Mo7W3 RHEA which exhibits an excellent combination of mechanical properties and wear resistance in a wide temperature range. The present RHEA possesses a yield strength of 1225 ± 17 MPa together with a fracture strain of > 45 % at room temperature, showing an excellent strength-ductility synergy. The alloy also maintains considerable yield strength and ductility at elevated temperatures, outperforming numerous ductile RHEAs. In addition, the coefficient of friction and wear rate decrease with increasing temperature from room temperature to 800 ℃. Interestingly, the alloy exhibits a wear rate as low as (5.50 ± 0.11) × 10−6 mm3 N−1 m−1 at 800 ℃, which is related to the formation of continues and dense oxide layer.