title: Bonding characteristics in NiAl intermetallics with O impurity: a first-principles computational tensile test.
abstract: We have performed a first-principles computational tensile test on NiAl intermetallics with O impurity along the [001] crystalline direction on the (110) plane to investigate the tensile strength and the bonding characteristics of the NiAl-O system. We show that the ideal tensile strength is largely reduced due to the presence of O impurity in comparison with pure NiAl. The investigations of the atomic configuration and bond-length evolution show that O prefers to bond with Al, forming an O-Al cluster finally with the break of O-Ni bonds. The O-Ni bonds are demonstrated to be weaker than the O-Al bonds, and the reduced tensile strength originates from such weaker O-Ni bonds. A void-like structure forms after the break of the O-Ni and some Ni-Al bonds. Such a void-like structure can act as the initial nucleation or the propagation path of the crack, and thus produce large effects on the mechanical properties of NiAl.
authors.affiliation: Department of Physics, Beijing University of Aeronautics and Astronautics, Beijing 100191, People's Republic of China.
authors.forename: Xue-Lan
authors.initials: XL
authors.lastname: Hu
authors.forename: Ying
authors.initials: Y
authors.lastname: Zhang
authors.forename: Guang-Hong
authors.initials: GH
authors.lastname: Lu
authors.forename: Tianmin
authors.initials: T
authors.lastname: Wang