Orientation relationship and interfacial structure between Nbsolid solution precipitates and α-Nb₅Si₃ intermetallics

The orientation relationship (OR) and the interfacial structure between Nb solid solution (Nbss) precipitates and α-Nb₅Si₃ intermetallics have been investigated by transmission electron microscopy (TEM). The OR between Nbss and α-Nb₅Si₃ was determined by selected-area electron diffraction analyses as (222)_Nb//(002)_α and . High-resolution TEM images of the Nbss/α-Nb₅Si₃ interface were presented. Steps existed at the interface that acted as centers of stress concentration and released the distortion of lattices to decrease the interfacial energy. In addition, the interfacial models were proposed based on the observed OR to describe the atomic matching of the interface. The distribution of alloying elements at the Nbss/α-Nb₅Si₃ interface has also been investigated, and Hf was enriched at the interface to strengthen the grain boundary.