Tensile strength and fracture property of Ni(111)/α-Al<sub>2</sub>O<sub>3</sub>(0001) interface with Yttrium doping based on first-principles

Abstract

The first principle calculations based on density functional theory are carried out to assess the tensile strength and fracture characteristics of Ni(111)/α-Al2O3(0001) interface with Yttrium doping in thermal barrier coating. At first, careful investigations are made to determine the computational models of the Al-terminated O-site Ni(111)/α-Al2O3(0001) interfaces, i.e., the physically possible occupied positions of reactive element Y among interstitial site, Al-substitution site and Ni-substitution site. By calculating the bonding energy of interfaces and comparing with that for clean Ni/Al2O3 interface, the stable Ni(111)/a-Al2O3(0001) interface model with reactive element Y is obtained. A detailed analysis of this interface is made on its atomic bonds and the lattice constants. Then, uniaxial tensile simulations by first-principle method are done to extract the fundamental mechanical properties of this interface, including theoretical tensile strength and work of separation. Furthermore, the failure and fracture characteristics of the interface are elucidated by observing the variations of the atomic bonds near interface and valence charge densities. Our study confirms that reactive element Y substantially strengthens the adhesion of Ni(111)/α-Al2O3(0001) interface.