Enhanced high-temperature strength of HfNbTaTiZrV refractory high-entropy alloy via Al2O3 reinforcement

Abstract

• Oxide dispersion-reinforced HfNbTaTiZrV alloy with multiple strengthening mechanisms is fabricated by the addition of Al 2 O 3 oxide. • Nanoscale Al 2 O 3 particles hinder the movement of dislocations and refine the grains from 80 to 13 μm. • The interstitial strengthening improves the high temperature softening resistance of the studied alloy. • 4 vol.%Al 2 O 3 -reinforced alloy displays superior compressive yield strength of 1392 MPa at 800 °C and 693 MPa at 1000 °C. • 4 vol.%Al 2 O 3 alloy displays notable characteristics of lightweight and high-temperature resistance. Novel composites of HfNbTaTiZrV refractory high-entropy alloy (RHEA) reinforced with 0–4 vol.% Al 2 O 3 particles have been synthesized by vacuum arc melting. The microstructure evolution, compressive mechanical properties at room and elevated temperatures, as well as strengthening mechanism of the composites were analyzed. The HfNbTaTiZrV RHEA reinforced with 4 vol.% Al 2 O 3 displayed excellent phase stability 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 was obtained for this composite. The improved yield strength resulted from multiple strengthening mechanisms caused by Al 2 O 3 addition, including solution strengthening, interstitial strengthening, grain boundary strengthening, and dispersion strengthening. Besides, the effects of interstitial strengthening increased with temperature and was the main strengthening mechanism at elevated temperatures. These findings not only promote the development of oxide-reinforced RHEAs for challenging engineering applications but also provide guidelines for the design of light refractory materials with multiple strengthening mechanisms.