Some unsolved aspects of Nitinol

Five unique and still unsolved aspects of Nitinol are introduced, pertaining to the ductility of the B2-phase as it relates to pseudotwinning, some unique observations of the R-phase, the stiffness of Nitinol during unloading, an unusual situation in which austenite can be stress induced from martensite, and an unusual deformation memory associated with subsequent modes of deformation.