Atomic structure of a {1 1 1} incoherent interface in Zr–N alloy Original Research Article

High-resolution transmission electron microscopy (HRTEM), crystallographic analyses and near-coincident-site atom modeling were used to investigate the atomic structure of a planar {1 1 1}ZrN interface between the Zr and ZrN phases in a Zr–33.9 at.% N alloy. The Zr and ZrN phases were found to have a high-index orientation relationship and display poor atomic matching across the {1 1 1}ZrN interface in the HRTEM images and using near-coincident-site atom modeling. These results show that the {1 1 1}ZrN interface is atomically incoherent and suggest that atomic faceting in the ZrN phase, rather than atomic matching at the interface, is the dominant factor in determining the {1 1 1}ZrN interface plane. Both the experimental HRTEM images and atomic model of the interface indicate that six (0 0 2)Zr planes correspond to nine (0 2 0)ZrN planes across the interface, so that it is mathematically rational. The interface is faceted at the micrometer-level and contains atomic steps, similar to partly coherent interfaces, indicating that such features cannot be used to define partial coherency at interfaces.