A comprehensive DFT study on the thermodynamic and mechanical properties of L12-Al3Ti/Al interface

Abstract

In this present work, we systematically studied the properties of metastable Al3Ti/Al (L12-Al3Ti/Al) low-index coherent interface, including structure stability, fracture behavior, plasticity, stacking fault energy, electron structure, and density of states by first-principles calculation. The results of the rigid scheme indicated that the strongest interfaces of L12-Al3Ti(001)/Al(001), L12-Al3Ti(110)/Al(110), and L12-Al3Ti(111)/Al(111) were stacked similarly to bulk L12-Al3Ti or Al, and the work of adhesion (Wad) of 2.78, 2.81, and 1.83 J/m2, respectively. In the rigid scheme, the theoretical tensile strength for L12-Al3Ti(001)/Al(001), L12-Al3Ti(110)/Al(110), and L12-Al3Ti(111)/Al(111) interfaces were 15.30, 14.23 and 12.39Gpa, respectively. We simulated the fracture behavior by the full-relaxed scheme, and tensile stresses are 10.65, 10.10, and 8.27 GPa for L12-Al3Ti(001)/Al(001), L12-Al3Ti(110)/Al(110), and L12-Al3Ti(111)/Al(111) interfaces, respectively. Furthermore, our findings revealed that the interfaces were prone to break on the Al side in the full-relaxed stretching scheme, which was closer to reality. Moreover, the partial density of states (PDOS) indicated that s-p-d hybridization orbitals formed among the Al and Ti atoms. Finally, unstable stacking fault energy and Rice ratio indicated that the L12-Al3Ti(001)/Al(001), L12-Al3Ti(110)/Al(110) interfaces had good plasticity to some extent. However, it can start slipping in <11-2> direction with D = 3.02 and turn into another direction after μ/b = 0.11.