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

Abstract : Deformation twinning of the Ti–25Ta–20Nb (mass%) shape memory alloy is characterized using EBSD and TEM. The selfaccommodating α″ microstructure is shown to be first deformed using \111\α″ type I and <211>α″ type II reorientation twinning. Plastic deformation occurs further by plastic twinning with a new \130\<310>α″ 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>α″ twinning variants during deformation. Analogy between \130\<310>α″ and \332\<113>β twinning systems is highlighted