Evidence for deformation-induced phase transformation in a high Sn content zirconium alloy

The zirconium alloy Excel has been shown to retain a metastable beta phase upon quenching from temperature within the alpha + beta phase field. Using a combination of neutron diffraction and EBSD, we show that it is possible to initiate a phase transformation from beta -> alpha during tensile deformation of Excel in the quenched state. We present a model to explain the observed behaviour. EBSD results show that twin-like alpha laths are formed in the beta grains during deformation. This beta -> alpha transformation shows a strong variant selection, as expected for a phase transformation that accommodates plastic strain. Secondary transformation laths were also observed which did not follow the expected variant rule. We present a simple model that explains quantitatively the behaviour of the beta -> alpha phase transformation during straining and accurately predicts the variant selection. (C) 2018 Published by Elsevier Ltd on behalf of Acta Materialia Inc.