ICTS

The omega phase, which is an equilibrium phase in Group 4 metals at high pressures, forms in several alloys of Ti, Zr and Hf and in many other bcc alloys as a metastable phase. The beta (bcc) to omega (hexagonal) transformation can be accomplished by introducing a periodic displacement of {222} planes of the parent bcc structure. In spite of being a first order transition, strong pre-transition effects, including phonon softening to a limited extent are observed in this case. Recent high-resolution electron microscopy work has revealed a number of interesting features which provide a clearer picture of the transformation mechanism.

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