Phase boundaries between A15 and D88 structures of the Nb-Ge compound system

The orientation relations of phase boundaries between grains of the cubic A15 phase and the hexagonal D88 phase in the Nb-Ge system have been investigated by high-resolution electron microscopy and selected-area electron diffraction techniques. By comparing the observed structure image with the image calculations for given boundary structure models, the atomic configuration of the phase boundary has been determined. The length of planar boundary segments of stepped boundaries has successfully been predicted by application of the phase-boundary theory of Bonnet and Durand.