Simple models for the omega phase transformation

Abstract

In the late sixties, it was recognized that the omega phase transformation occurring in bcc Ti, Zr, and Hf alloys was a displacive transition which could be described, at least qualitatively, by simple models. Since the displacive wave responsible for the transition to perfect omega was a Brillouin zone boundary wave, displacements and volume changes were rather small, in contrast to the classical martensite case. The nonideal, or modulated omega phase requires further consideration, and calls for soliton models, for example. Recent first principles electronic structure calculations, briefly reported upon here, have also shed light on the athermal omega transformation.