The Structure of the Nb–γ-Nb5Si3 Interface in in-situ Nb–Si Eutectic Composites

The orientation relationship between the niobium matrix and γNb5Si3 silicides: [111]Nb//[0001]γ and (110)Nb//(10$$\bar {1}$$0)γ in the Nb–Si eutectic composite has been determined in this work. Within the edge-to-edge matching model, an estimation of the size misfit between the interatomic and interplanar distances of the matched phases has been made. Using direct resolution transmission electron microscopy, the structure of the interfaces between the bcc lattice of the niobium matrix and the hcp lattice of γNb5Si3 silicide was studied. At matched interfaces, boundary misfit dislocations, indicating a semicoherent nature of the coupling between the phases, are discovered. The step-like structure of the interphase boundary is analyzed.