First-principles calculations on interface structure and fracture characteristic of TiC/TiZrC nano-multilayer film based on virtual crystal approximation

Highlights: • Calculated result by VCA model is in fully consistent with that by conventional model. • Possible TiC (100)/TiC (100) and TiC (100)/TiZrC (100) interfaces were established. • Chemical bond formed at interface shows covalent character and ionic character. • Sustainable imposed stress of TiC/TiC interface is higher than that of TiC/TiZrC interface. TiC (100)/TiC (100) interface and TiC (100)/TiZrC (100) interface were studied by first-principles calculation based on virtual crystal approximation for developing the novel TiC/TiZrC nano-multilayered film. Surface convergence calculation result demonstrates that both TiC slab and TiZrC slab with more than five atom-layers exhibit bulk-like interiors. Geometry models of TiC (100)/TiC (100) interface and TiC (100)/TiZrC (100) interface with different termination structures were constructed. The calculated interfacial work of adhesion and relaxed interfacial distance show that for both TiC (100)/TiC (100) interface and TiC (100)/TiZrC (100) interface, Ti-C termination structure is always more stable than C-C termination structure. The reason is that the Ti-C termination structure can maintain the alternating stacking of cations and anions at interface. Moreover, because that the covalent bonding strength and ionic bonding strength of TiC (100)/TiC (100) interface are larger than those of TiC (100)/TiZrC (100) interface, TiC (100)/TiC (100) interface shows the stronger interface stability. The tensile fracture process indicates that for TiC (100)/TiC (100) interface, the fracture occurs between the 2′ and 1′ layers in TiC (100) slab. While for TiC (100)/TiZrC (100) interface, the fracture occurs at the interface. Moreover, the sustainable imposed stress of TiC (100)/TiC (100) interface is much higher than that of TiC (100)/TiZrC (100) interface.