Improved oxidation resistance of (Ti-Zr-Hf-V-Nb-Ta)CoSb high-entropy half Heulser

The oxidation behaviour of a high-entropy half Heusler (HEHH) alloy is reported, for the first time, in comparison with its medium- and low-entropy counterparts. TG-DSC analysis demonstrates that HEHH powder exhibits enhanced oxidation resistance, as evidenced by higher oxidation weight change temperature (WCT) compared to medium- and low-entropy half Heusler alloys, which is attributed to high-entropy effects and superior structural stability. Additionally, the aged HEHH bulk sample shows a thinner oxidation layer compared with medium-entropy alloys, further confirming the improved oxidation resistance of HEHH alloy. • Oxidation behaviour (RT-750°C) of (Ti-Zr-Hf-V-Nb-Ta)CoSb (HEHH) was compared with low/medium-entropy alloys. • HEHH exhibits the highest onset temperature for weight change (555 ℃). • HEHH shows a delayed, diffusion-controlled oxidation process. • Improved oxidation resistance of HEHH may be attributed to the high entropy effect.