Abstract: Based on the first-principle caluclation,the lattice vibrational effects on the phase stability of Ti-Al system are studied by using the cluster variation method.In this study,two models,i.e.the continuous Medium model and the lattice dynamics model (atomic pair potential is obtained by M?bius inversion),are considered.For the former,the effect from the lattice vibration on the phase stability is negligible,while for the latter model,it is obvious.This result indicates that the optical mode of the lattice vibration is important when the lattice vibrational effects on the alloy's phase stability are considered taken into account.

Key words: LMTO, CVM, lattice vibration, phase stability