Deformation twinning in the full-α martensitic Ti-25Ta-20Nb shape memory alloy

Deformation twinning of the Ti-25Ta-20Nb (mass%) shape memory alloy is characterized using EBSD and TEM. The selfaccommodating alpha '' microstructure is shown to be first deformed using (111)(alpha '') type I and < 211 >(alpha '') type II reorientation twinning. Plastic deformation occurs further by plastic twinning with a new {130}< 310 >(alpha '') twinning system. Maximum lattice deformation calculation is a relevant parameter to predict the variant of martensite that is favored during the reorientation process. Conversely, Schmid factor analysis can be used to predict the selection of {130}< 310 >(alpha '') twinning variants during deformation. Analogy between {130)< 310 >(alpha '') and (332)< 113 >(beta) twinning systems is highlighted. (C) 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.