Site occupancy in solid solutions of Nb in the intermetallic compounds TiAl and Ti3Al

Strengthening of γ-TiAl-Nb by short-range ordering of point defects

“…The formation energy of Nb Al (0.955 eV) is slightly higher than that of the composition-conserving Nb Ti þTi Al complex (0.943 eV), indicating that Nb atoms prefer to occupy Ti-sublattice even in Ti-rich TiAl. This result is in agreement with the experiments which demonstrated that, for the TiAl-Nb alloys with relatively low Nb concentration, Nb atoms occupies solely the Ti-sublattice regardless the relative concentrations of Ti and Al [18,19]. The occupancy of Nb in TiAl is somehow out of the general trend of the site-occupations of alloying atoms in intermetallic compounds since it seems natural for the alloying atoms to fill the sublattice of the component in deficiency.…”

Spinodal decomposition of the γ-phase upon quenching in the Ti–Al–Nb ternary alloy system

“…Morphological similarities were found between the h-phase within the TiAl matrix and the g-phase transformation observed in this study. A structural model was generated using the Crystal Maker software package from the reported structural data for both the gTiAl [25,26] and the h-Al 2 Ti phases [22] and are reproduced in Fig. 5.…”

Thermodynamic activities in the alloys of the Ti-Al-Nb system

“…This means that the order on the Al sublattice increases and that on the Ti sublattice decreases atoms between the two lattices as a consequence of the preference of Nb for the Ti sublattice can be explained by the Nb addition. The order on the Ti sublattice decreases emission electron-beam channeling experiments carried out by Konitzer et al [42] using analytical transmission electron microscopy. They report that the Nb is preferentially situated on the Ti sublattice.…”