Abstract
The austenite and martensite phases of Fe-9.70% Al-1.46% C steel have been observed by means of transmission electron microscopy and electron diffraction. It was verified that the austenite γ phase has a superlattice of the Cu3Au type, and the assumption in a previous paper (Trans. JIM, 11(1970), 152) that the martensite lattice would be formed by the Bain distortion from the Cu3Au type ordered γ lattice was confirmed unambiguously. Besides, it was found that the ordered γ phase consists of anti-phase domains of about 120 Å size. From the appearance of cross streaks around the fundamental spots as well as superlattice spots in the ⟨100⟩ directions, the anti-phase domain boundaries were identified to be of the second type.
