Atomic Scale Insight into the Oxidation Mechanism of Nb/Ta‐Doped Ti3SiC2/Al2O3 Ceramics

The low oxidation resistance of Ti 3 SiC 2 /Al 2 O 3 composites limits their applications as high‐temperature structural materials. To improve the oxidation resistance, Nb and Ta are introduced into the substrate herein. The Nb/Ta‐doped Ti 3 SiC 2 /Al 2 O 3 composite shows superior oxidation resistance than clean Ti 3 SiC 2 /Al 2 O 3 following the oxidation process at 800–1000 °C for 100 h. The oxidation mechanism is determined via first‐principles calculations. The oxidation process of the composite is controlled by the inward diffusion of O and outward diffusion of Ti. When Nb/Ta elements are doped, their larger atomic radii and stronger binding produce a higher diffusion barrier for O and Ti atoms, which prevents element migration and reduces the thickness of the oxidation layers.