Enhanced High-Temperature Strength of HfNbTaTiZrV Refractory High-Entropy Alloys by AI 2O 3 Reinforcement

The HfNbTaTiZrV refractory high-entropy alloy reinforced with 4vol.% Al₂O₃ displays excellent phase stability and mechanical properties at elevated temperatures. A superior compressive yield strength of 2700 MPa at room temperature, 1392 MPa at 800 °C, and 693 MPa at 1000 °C has been obtained. The improved yield strength results from multiple strengthening mechanisms caused by Al₂O₃ addition, including interstitial strengthening, grain boundary strengthening, and dispersion strengthening. Besides, the effects of interstitial strengthening increase with the temperature and is the main strengthening mechanism at 800 °C. These findings not only promote the development of oxide-reinforced RHEAs for challenging engineering applications but also provide guidelines for the design of refractory materials with multiple strengthening mechanisms.