Publication detail

In situ synchrotron X-ray diffraction analysis of two-way shape memory effect in Nitinol

WANG, Z. ZHANG, Y. LIOGAS, K. CHEN, J. VUGHAN, G. KOCICH, R. KUNČICKÁ, L. UZUN, F YOU, Z KORSUNSKY, A

English title

In situ synchrotron X-ray diffraction analysis of two-way shape memory effect in Nitinol

Type

journal article in Web of Science

Language

en

Original abstract

Despite the fact that the Two-Way Shape Memory Effect (TWSME) has been demonstrated in most Shape Memory Alloys, the effective application of this unique functional behaviour is hindered by the lack of a proper training methodology and understanding of its mechanisms. In this study, a novel training routine has been established together with a home-designed device, enabling TWSME of customised spline curvature to be produced. An in situ high energy synchrotron X-ray diffraction experiment has been performed on Nitinol, followed by comprehensive analysis to reveal the micromechanics of TWSME. Multiple mainstream hypotheses have been examined. The important findings are: (1) The training process has negligible influence on the texture of parent phase; (2) The preferred variant of the B19’ phase exhibits tension/compression asymmetry in TWSME; (3) (100) compound twin is the preferred deformation mode for compression TWSME; (4) The mesoscale residual strain field is the dominant factor that induces TWSME; (5) Lattice defects (dislocations) are spatially rearranged after training; (6) Compression TWSME training retards the B2 to B19’ transformation, whilst tension has the opposite effect. The implications of these findings are further discussed.

English abstract

Despite the fact that the Two-Way Shape Memory Effect (TWSME) has been demonstrated in most Shape Memory Alloys, the effective application of this unique functional behaviour is hindered by the lack of a proper training methodology and understanding of its mechanisms. In this study, a novel training routine has been established together with a home-designed device, enabling TWSME of customised spline curvature to be produced. An in situ high energy synchrotron X-ray diffraction experiment has been performed on Nitinol, followed by comprehensive analysis to reveal the micromechanics of TWSME. Multiple mainstream hypotheses have been examined. The important findings are: (1) The training process has negligible influence on the texture of parent phase; (2) The preferred variant of the B19’ phase exhibits tension/compression asymmetry in TWSME; (3) (100) compound twin is the preferred deformation mode for compression TWSME; (4) The mesoscale residual strain field is the dominant factor that induces TWSME; (5) Lattice defects (dislocations) are spatially rearranged after training; (6) Compression TWSME training retards the B2 to B19’ transformation, whilst tension has the opposite effect. The implications of these findings are further discussed.

Keywords in English

Two-way shape memory effectIn situ synchrotron X-ray diffractionNitinolMicromechanics

Released

01.06.2023

Publisher

ELSEVIER SCIENCE INC

ISSN

0921-5093

Volume

878

Number

145226

Pages count

12

BIBTEX


@article{BUT184111,
  author="Radim {Kocich} and Lenka {Kunčická},
  title="In situ synchrotron X-ray diffraction analysis of two-way shape memory effect in Nitinol",
  year="2023",
  volume="878",
  number="145226",
  month="June",
  publisher="ELSEVIER SCIENCE INC",
  issn="0921-5093"
}