Investigation of the structure and composition of a {111} incoherent Zr/ZrN interface containing ledges by high-resolution transmission electron microscopy, image simulation, electron energy-loss spectroscopy, energy-filtering transmission electron microscopy, and near-coincidence-site analysis

Abstract

Investigation of the atomic structure of a (111) Zr/ZrN interface shows that it is a type-3 incoherent interface (i.e., high-index orientation relationship with a low-index interface plane in only one phase), as determined from conventional transmission electron microscopy (TEM) and high-resolution TEM (HRTEM) images, image simulations, and near-coincidence-site atomic modeling of the interface. Long facets and atomic ledges several {111}ZrN planes high form at the interface, indicating that such features cannot be used as criteria to define partial coherency at interfaces. These results also indicate that ledgewise growth is possible during the phase transformation from Zr to ZrN. Composition profiles taken across the interface using energy-filtering TEM and the N K-edge show that the composition changes abruptly at the interface, in accord with the structural transformation. Simulation results on an inclined (111) Zr/ZrN interface indicate that it is possible to judge whether an interface is inclined and faceted at the same time. A rough interface can look faceted in a HRTEM image due to projection effects, but only under a very strict set of conditions. Conversely, an interface cannot be faceted if it looks rough in an HRTEM image.