Long-Period Antiphase Domain Structures of Al-Ti Alloys near Composition Al₃Ti

Abstract

Superstructures of Al-Ti alloys in the composition range from Al3Ti to Al2Ti were studied by electron diffraction. It was shown that the Al24Ti8 which has been reported to be a low temperature modification of the Al3Ti phase has a long-period one-dimensional antiphase domain structure (1d-APS) with average domain size M=8/6, where M is measured in unit cell length of the fundamental lattice. In addition, the 1d-APS's with M=1.60–1.91 were found in the specimens containing 26.5 to 32.5 at.% Ti and it was suggested that the 1d-APS's with M=1.67–1.91 correspond to the high temperature phase Al5Ti2 (or Al11Ti5).