High-strain induced reverse martensitic transformation in an ultrafine-grained Ti-Nb-Ta-Zr alloy

• Published in: Philosophical magazine letters Vol. 96; no. 5; pp. 189 - 195
• Main Authors: Li, Zhiming, Zheng, Baolong, Kurmanaeva, Lilia, Zhou, Yizhang, Valiev, Ruslan Z., Lavernia, Enrique J.
• Format: Journal Article
• Language: English
• Published: Abingdon Taylor & Francis 03.05.2016; Taylor & Francis Ltd
• Subjects: Equal channel angular pressing; equal channel angular pressing (ECAP); Grain size; Martensite; Martensitic stainless steel; Martensitic transformations; Materials science; Phase transformations; Reduction; Strain; Titanium alloys; Titanium base alloys; Transforms; Transmission electron microscopy; ultrafine-grained materials
• ISSN: 0950-0839; 1362-3036
• DOI: 10.1080/09500839.2016.1189098

We report on a novel phenomenon, that is a high-strain-induced reverse martensitic transformation in an ultrafine-grained Ti-36Nb-2Ta-3Zr (wt.%) alloy processed by equal channel angular pressing (ECAP) at room temperature. Our results show that a martensitic transformation from body-centred cubic β matrix to orthorhombic α″ martensite occurs under low-strain ECAP conditions and that a large portion (~34%) of martensite transforms into a matrix phase (i.e. reverse martensitic transformation) with increasing ECAP strain to a high value of 4 (i.e. 6 passes) with a corresponding reduction in the α″-lath thickness and a refinement of grain size in the matrix phase.