Tensile deformation of superelastic NiTi wires in wide temperature and microstructure ranges

0517463 - FZÚ 2020 RIV DE eng J - Journal Article
Chen, Y. - Tyc, Ondřej - Molnárová, Orsolya - Heller, Luděk - Šittner, Petr
Tensile deformation of superelastic NiTi wires in wide temperature and microstructure ranges.
Shape Memory and Superelasticity. Roč. 5, č. 1 (2019), s. 42-62. ISSN 2199-384X. E-ISSN 2199-3858
R&D Projects: GA MŠMT(CZ) LM2015088; GA ČR GA18-03834S; GA ČR GA16-20264S
Institutional support: RVO:68378271
Keywords : NiTi * superelasticity * tensile test * heat treatment * TEM observation of lattice defects
OECD category: Condensed matter physics (including formerly solid state physics, supercond.)
Method of publishing: Open access

Superelastic NiTi wires were prepared from a single cold worked wire by various electropulse heat treatments. The wires having a wide range of virgin microstructures were subjected to tensile tests until rupture and cyclic superelastic tensile testing in a wide temperature range. The results were complemented by TEM observation of lattice defects created by superelastic cycling. It appeared that the yield stress depends significantly on the wire microstructure and less on the test temperature. The upper plateau stress varies with the microstructure through its effect on the Ms temperature and increases with increasing temperature in accord with the Clausius–Clapeyron equation up to a maximum temperature characteristic for each microstructure. The upper plateau strains exhibit pronounced maxima (12–18%) at test temperatures and microstructures (pulse times), at which the upper plateau stress approaches the yield stress.

Permanent Link: http://hdl.handle.net/11104/0302766