RETRACTED: Precipitation behavior of Al-Ti-Ag alloy system (Retracted article. See vol. 21, pg. 614, 2015)

Transmission electron microscopy (TEM) examinations of Al3Ti with an L1(2)-ordered structure have revealed the precipitation of D0(23)-Al11Ti5 and L1(0)-TiAl upon aging after quenching from higher temperatures. TEM observations revealed that fine uniform precipitation of Al2Ti occurs when the supersaturation is sufficiently high, and, a preferential precipitation at the antiphase boundaries can be observed in alloy with a low supersaturation. When L1(2)-Al3Ti is supersaturated with DO22-Al3Ti, DO23-Al11Ti5 with a multidomain structure is formed during aging. On the other hand, plate-like L1(0)-TiAl precipitates lie on the {001} planes of (Al,Ag)(3)Ti matrix in the short aging period and the habit plane changed from {001} to {hhl} after a long period aging or higher temperature aging and finally to {225} of the matrix lattice. The Ll(2) phase field in the Al-Ti-Ag system is severely skewed with respect to the temperature axis and is restricted into a much smaller field at lower temperatures. Appreciable hardening and overage softening during aging can be explained in terms of microstructural variations.