Adhesion, stability and electronic properties of Ti2AlN(0001)/TiAl(111) coherent interface from first-principles calculation

This research work aims at investigating the adhesion, stability and electronic properties of Ti2AlN(0001)/TiAl(111) coherent interface by first-principles calculation based on density functional theory. Twelve kinds of Ti2AlN(0001)/TiAl(111) interfacial models were investigated in consideration of two different Ti2AlN(0001) surface terminations, three different interfacial atom stacking sites, and two different atomic layer stacking sequences of TiAl(111) surface slab. The adhesive work, interfacial energy, electronic structure of the interface models were calculated. The results show that the adhesive work of Ti(Al)-terminated Ti2AlN(0001)/TiAl(111) interface is larger than that of Al-terminated Ti2AlN(0001)/TiAl(111) interface. For both the Ti(Al)- and Al-terminated Ti2AlN(0001)/TiAl(111) interface, the adhesive work increases, and the interfacial energy decreases as the order of on-top, hcp-hollow and fcc-hollow sites. For the interfaces with same interfacial termination and stacking site, the atomic layer stacking sequence of TiAl(111) surface slab has a weak influence on the adhesive work and interfacial energy. The Ti(Al)-terminated Ti2AlN(0001)/TiAl(111) interface with the stacking site of fcc-hollow and stacking sequence of “(Ti2AlN)ABABA-C′B′A′C′B′(TiAl)” shows the largest adhesive work (2.99 J/m2) and lowest interfacial energy (0.57 J/m2). The calculated electronic properties reveal that the interfacial bonding of Ti(Al)-terminated Ti2AlN(0001)/TiAl(111) interface is mainly contributed from Ti-Al covalent and Ti-Ti metallic interactions, and the dominant interfacial bonding is Al-Al metallic and Ti-Al covalent bonds for Al-terminated Ti2AlN(0001)/TiAl(111) interface. The interfacial bond strength of Ti(Al)-terminated interface is stronger than that of Al-terminated interface.