Affiliations: [a] Institute of Fundamental Technological Research,
Polish Academy of Sciences, Swi�tokrzyska 21, 00-049 Warsaw, Poland | [b] Department of Mechanical Engineering, AICHI Institute
of Technology, 1247, Yachigusa, Toyota-city, Aichi, 470-0392, Japan. E-mail:
[email protected]
Correspondence:
[*]
Corresponding author: Elzbieta Alicja Pieczyska, Institute of
Fundamental Technological Research, Polish Academy of Sciences, Swietokrzyska
21, 00-049 Warsaw, Poland. Tel.: +48 22 8261281; Fax: +48 22 826 98 15; E-mail:
[email protected]. AICHI Institute of Technology, 1247, Yachigusa,
Toyota-city, Aichi, 470-0392, Japan. Tel.: +81 565 48 8121; Fax: 81 565 48
4555; E-mail: [email protected]
Abstract: Martensitic and reverse transformations in TiNi shape memory alloy
subjected to tension test at room temperature are investigated using a
thermovision camera. Stress relaxation stages during the loading and unloading
branches are induced, respectively. A very large stress drop, caused by the
phase transformation, is observed during the stress relaxation in both the
course of loading and unloading, while, for the temperature-controlled test, in
the unloading branch the stress increases under constant strain; due to the
recovery. The non-uniform temperature distribution reflecting the inhomogeneous
phase transformation at its initial stage is observed to start again at the end
of the relaxation break and develop during the reloading process.
Keywords: TiNi shape memory alloy, phase front, stress relaxation
