The atomistic structure and energies of high-index interphase boundaries are explored using a combination of molecular statics and dynamics simulations with embedded atom potentials. We investigate planar boundaries between the α^sub 2^ and γ phases in the Ti-Al system. The class of boundaries considered has a high-index boundary orientation; the orientation relationship between the α^sub 2^ and γ phases also is high index, and a set of planes from each phase meet edge to edge at the boundary plane. For the particular case of a boundary that is commensurate in one direction and coincides with a moiré plane given by the so-called "Δg" diffraction condition, the boundary is not structurally singular, but it is energetically stable and does not appear to dissociate into other low-energy configurations. Misfit compensating defects are not observed: misfit in directions other than the commensurate one appears to be distributed uniformly. The boundary energy is evaluated as a function of the orientation of the boundary plane, and the edge-to-edge (moiré) boundary is found to lie in an energy cusp. PUBLICATION ABSTRACT