ATOMIC-SCALE ANALYSIS OF MARTENSITIC-TRANSFORMATION IN TITANIUM ALLOYED WITH VANADIUM .1. VERIFICATION OF THE EMBEDDED-ATOM METHOD MODEL

The embedded-atom method type interatomic potentials for h.c.p. titani um and b.c.c, vanadium, originally proposed by Johnson and coworkers, were modified in order to be able to model both the b.c.c. and the h.c .p. structures and the phase transformation between the two in titaniu m-base Ti-V alloys. The reliability of the modified potentials was tes ted with respect to lattice dynamics (the phonon dispersion curves and the phonon density of states) in the two structures and with respect to the relative thermodynamic stability of the two phases as a functio n of temperature and the alloy composition. The model predictions are found to be in reasonable agreement with their experimental counterpar ts. In particular, the predicted effect of vanadium on two phonon mode s, a T-1 N-point 1/2[110] phonon and T-1 [112] phonon, which play the key roles in the b.c.c. --> h.c.p. transformation, was found to be con sistent with the experiment.