Oxide dispersion strengthening mediated ultra-high strength at wide temperature range in NbTaTiV refractory high-entropy alloys

Abstract

The NbTaTiV-based refractory high-entropy alloys (RHEAs) show promising high-temperature properties and excellent processability. However, achieving ultra-strong strengths while maintaining room-temperature processability is still a challenge. In this work, a new ultra-strong NbTaTiV RHEA reinforced with 0.35 wt% Al2O3 was successfully designed and synthesized. The characteristics of oxides and their effects on mechanical properties were systematically studied. It was found that the Al2O3 will fully disperse and reacted with NbTaTiV RHEA after milling and sintering at 1600 °C, leading to the in-situ formation of dispersive Ti-(O, N) particles and the dissolving of Al atoms. The dual-phase RHEA exhibited a superior combination of yield strength (2075 MPa) and compressive plasticity (15%) while keeping high strength at a wide temperature range (25–1000 °C). The ultra-strong strength of the present dual-phase RHEA is mainly attributed to the particle strengthening caused by the high dispersion of Ti-(O, N) submicron particles and the solid solution strengthening from the dissolved Al and interstitial atoms. It is revealed that RHEAs can be remarkably enhanced through oxide dispersion strengthening and solution strengthening, which provides a new sight for designing high-performance RHEAs.