We report results from an experimental and theoretical study of the ternary alloy Ti-6Al-4V to 221 GPa. We observe a phase transition to the hexagonal Ï phase at approximately 30 GPa, and then a further transition to the cubic β phase starting at 94-99 GPa. We do not observe the orthorhombic γ and δ phases reported previously in pure Ti. Computational studies show that this sequence is possible only if there is significant local atomic ordering during the compression process, yet insufficient atomic diffusion to reach the phase-separated thermodynamic equilibrium state.