Mechanical and tribological performance of AlCr0.5NbTaxTi4-x ( x=0, 0.5, 1) refractory high-entropy alloys

The tribological behavior of AlCr0.5NbTaxTi4-x ( x = 0, 0.5, and 1) refractory high-entropy alloys was sys-tematically investigated from room temperature to 800 degrees C. The relationship between the alloy composi-tion, microstructure, mechanical properties, and tribological performance was analyzed. The results show that all three alloys have a body-centered cubic (bcc) single-phase structure. The Ta addition enhances solid solution strengthening and increases the melting point that would resist high-temperature ther-mal softening. As a result, high-temperature strength is enhanced considerably, the coefficients of friction (COF) and wear rates of the alloys are reduced considerably at elevated temperatures, demonstrating ex-cellent friction-reducing and anti-wear properties, e.g., the COF and wear rate of AlCr0.5NbTaTi3 alloy at 800 degrees C are 0.34 and 4.40 x 10 -7 mm3 N -1 m -1 , respectively. The excellent wear resistance at high temper-atures can be attributed to the formation of an oxide-tribo layer (Ta2O5 and TiO2) with ultrafine-grained layers and good high-temperature mechanical properties.(c) 2023 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.