Transmission electron microscopy observations of structural modulation in the phase transition from α-Zr to ω-Zr induced by shear strain

Pure alpha-Zr samples were processed using unconstrained die sets at 5 and 6 GPa with different numbers of revolutions. The microstructural characteristics of Zr deformed by high pressure torsion was studied using transmission electron microscopy. It was found that shear strain can induce distortion of the hcp structure, which can, in addition, give rise to a variety of modulated structures. Most importantly, one possible phase transition route from alpha-Zr to omega-Zr is proposed involving intermediate steps with structural modulations. (c) 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.