A hierarchical high-throughput first principles investigation on the adhesion work, interfacial energy and tensile strength of NiTi₂ (100)/α-Al₂O₃ (0001) interfaces

By performing a high-throughput first principles calculations on works of adhesion of total 468 different NiTi₂/Al₂O₃ interfaces, eight interfacial configurations (Ni1–O, Ni2–O, Ti1–O, Ti2–O, Ni1–Al2, Ni2–Al1, Ni2–Al2 and Ti2–Al2) belonging to metal–metal and metal–oxygen interfaces are obtained due to their high adhesive strengths. The predicted work of adhesion of metal–oxygen interfaces is higher than 8.80 J/m², and that value of metal–metal interfaces varies in the range from 2.39 J/m² to 3.59 J/m². The interfacial energies of the eight interfaces are obtained at different temperatures (298 K and 1000 K) by varying the chemical potential of oxygen atom. At room temperature, the metal–oxygen interfaces possess the lower interfacial energies and thus the higher thermodynamic stability than those of metal–metal interfaces regardless of the partial pressure of oxygen gas. At high temperature, metal–oxygen interfaces are still favored under O-rich condition, but the metal–metal interfaces are greatly stabilized in case of low oxygen partial pressure. The predicted tensile strengths of metal–oxygen interfaces are all above 10 GPa, and those of for metal–metal interfaces are below this value. For all investigated metal–metal and metal–oxygen NiTi₂/Al₂O₃ interfaces, the mechanical failure is always initiated in the NiTi₂ phase proximity to the interface resulted from the breaking of Ni–Ti/Ti–Ti bonds in the first principles tensile test.