Such boundaries in the  phase, which formed during    massive transformations in a 48at%Al alloy, were investigated by means of high-resolution electron microscopy. It had previously been shown, using an electron micro-diffraction method, that thin rotated domain walls formed at the boundaries. The detailed structure of such a thin rotated domain wall, with respect to that of the matrix, was here clarified at the atomic scale. The main results were the existence of an antiphase relationship between the regions on either side of the thin rotated domain, and a local lattice distortion in the thin rotated domain wall region. Complex antiphase boundary fringe contrasts in the massively transformed  phase could thus be explained. The formation of thin rotated domain walls during the massive transformation was explained in terms of the antiphase boundary energy of the  phase.

E.Abe, M.Nakamura: Philosophical Magazine Letters, 1997, 75[2], 65-73