Microscopic mechanism of the effect of Nb and Cr co-doping on the strength and ductility of Ti2AlC/Ti3Al coherent interface

We employ first-principles calculations to study the adhesion work, interface energy, and electronic structure of Ti2AlC/Ti3Al interfaces. A novel interface mismatch model is proposed, and the interface mismatch degrees of Ti2AlC/Ti3Al interfaces are discussed and analyzed. The results show that the TiAl2-C coherent interface structure exhibits the highest adhesion work and the lowest interface energy, indicating that it has the greatest interfacial bonding strength and stability. The bonding properties of the Cr/Nb co-doped interface are evaluated through tensile strain calculations. The doping of Cr at the interface and Nb at the second layer near the interface significantly enhances the tensile strength and fracture toughness of the interface. This is due to the formation of strong covalent bonds between Cr, Ti, and C at the interface, as well as the presence of strong interactions between Cr and Nb at the fracture area. These findings are of significant importance for improving the performance of TiAl alloys and for the design and development of high-performance TiAl matrix composites materials. [Display omitted]