Abstract
The decomposition process of melt extracted Ti-25 at.% Al-25 at.% Nb has been studied by transmission electron microscopy. During the decomposition process, diffuse streaking and diffuse extra maxima were observed in the diffraction patterns of this alloy. The diffuse streaking is caused by the intersection of the Ewald sphere and the octahedral surfaces which are composed of eight relplanes. The diffuse maxima can be indexed as a trigonal phase with lattice parameters a = 0.4575 nm and c = 0.5604 nm. The crystal structure of several ω-related phases are also discussed. The rapidly solidified Ti-Al-Nb ribbon does show an improvement in ductility but unfortunately after annealing loses its ductility.