Abstract
The phenomenological theory of martensitic transformations is applied to the various observed transformation modes in the shape memory alloy nickel-titanium. Since the martensitic phase has a crystal structure which can be considered to be a monoclinic distortion of the orthorhombic B19 structure of gold-cadmium and is twinned internally, a treatment based on the formulation of Lieberman. Wechsler and Read has been used. New experimental evidence is presented to show that one of the observed twinning modes in the martensite can be identified as a type II mode, with the shear direction η 1 being derived from a cell edge of the parent B2 phase. The theoretical predictions for this mode and the mode where the twinning is type I with K 1 = (11 1 ̄ ) M are found to be in satisfactory agreement with the available experimental results. A third twinning mode, of Type I with K 1 = (001) M is shown to be unable to produce the lattice invariant shear necessary in the martensitic transformation.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
