Order-disorder transformation for TiAl with L1₀ structure at stoichiometrical composition

The embedded atom method (EAM) was used to study the order-disorder transformation in γ-TiAl alloy with L1₀ structure at stoichiometrical composition, and the effect of lattice constants was also investigated. It is found that the γ-TiAl alloy at stoichiometrical composition exhibits a second-order transition and the relations between lattice constants a, c and the long-range order σ are not linear. The lattice constant a decreases whereas c increases with the increase of long order parameter. In this case the ordering induces the transformation from cubic to tetragonal. The change of the lattice constant during the ordering processes can be interpreted in terms of bond length.