Publication detail

Proposition of R-phase transformation strip in the phase diagram of Ni-Ti shape memory alloy using electromechanical experiments

SHAYANFARD, P. KADKHODAEI, M. SAFAEE, S.

English title

Proposition of R-phase transformation strip in the phase diagram of Ni-Ti shape memory alloy using electromechanical experiments

Type

journal article in Web of Science

Language

en

Original abstract

The shape memory mechanism associated with R-phase transformation was investigated using electromechanical tests on Ni-Ti shape memory alloy thin wires. To provide a more precise insight into the effects of R-phase on phase transformation of shape memory alloys, wires were prepared in three different initial states prior to conducting the experiments: pure martensite, mixture of R-phase and martensite, and pure R-phase. The electromechanical tests were done in two different loading states (under constant and variable stresses) using specially designed and manufactured apparatuses. Tests under different constant stresses were carried out for three cases of pure martensite, a mixture of martensite and rhombohedral, and pure rhombohedral phase, while those under variable stresses were done on pure martensite as well as mixed martensite and rhombohedral. For all the expressed cases, strain-time responses were investigated during electric heating-cooling cycles to interpret possible microstructural changes in the samples. According to the results, a phase diagram containing R-phase transition strip was proposed for Ni-Ti shape memory alloys.

English abstract

The shape memory mechanism associated with R-phase transformation was investigated using electromechanical tests on Ni-Ti shape memory alloy thin wires. To provide a more precise insight into the effects of R-phase on phase transformation of shape memory alloys, wires were prepared in three different initial states prior to conducting the experiments: pure martensite, mixture of R-phase and martensite, and pure R-phase. The electromechanical tests were done in two different loading states (under constant and variable stresses) using specially designed and manufactured apparatuses. Tests under different constant stresses were carried out for three cases of pure martensite, a mixture of martensite and rhombohedral, and pure rhombohedral phase, while those under variable stresses were done on pure martensite as well as mixed martensite and rhombohedral. For all the expressed cases, strain-time responses were investigated during electric heating-cooling cycles to interpret possible microstructural changes in the samples. According to the results, a phase diagram containing R-phase transition strip was proposed for Ni-Ti shape memory alloys.

Keywords in English

electromechanical; phase diagram; R-phase; shape memory alloy

Released

21.03.2017

Publisher

SAGE PUBLICATIONS LTD

Location

LONDON

ISSN

1045-389X

Volume

28

Number

19

Pages from–to

2757–2768

Pages count

12

BIBTEX


@article{BUT164601,
  author="Pejman {Shayanfard},
  title="Proposition of R-phase transformation strip in the phase diagram of Ni-Ti shape memory alloy using electromechanical experiments",
  year="2017",
  volume="28",
  number="19",
  month="March",
  pages="2757--2768",
  publisher="SAGE PUBLICATIONS LTD",
  address="LONDON",
  issn="1045-389X"
}