Recoverability of large strains and deformation twinning in martensite during tensile deformation of NiTi shape memory alloy polycrystals

0511540 - FZÚ 2020 RIV GB eng J - Journal Article
Chen, Y.C. - Molnárová, Orsolya - Tyc, Ondřej - Kadeřávek, Lukáš - Heller, Luděk - Šittner, Petr
Recoverability of large strains and deformation twinning in martensite during tensile deformation of NiTi shape memory alloy polycrystals.
Acta Materialia. Roč. 180, Nov (2019), s. 243-259. ISSN 1359-6454. E-ISSN 1873-2453
R&D Projects: GA MŠMT(CZ) EF16_019/0000760; GA MŠMT(CZ) LM2015088; GA ČR GC17-00393J; GA ČR GA18-03834S
Grant - others:OP VVV - SOLID21(XE) CZ.02.1.01/0.0/0.0/16_019/0000760
Institutional support: RVO:68378271
Keywords : plastic-deformation * localized deformation * b2 phase * transformation * temperature * mechanisms * behavior * wires * energetics * slip * NiTi * superelasticity * shape memory alloy * tensile test * large deformation * martensitic transformation * deformation twinning * transmission electron microscopy
OECD category: Condensed matter physics (including formerly solid state physics, supercond.)
Impact factor: 7.656, year: 2019
Method of publishing: Limited access
https://doi.org/10.1016/j.actamat.2019.09.012

Superelastic NiTi wires were deformed in tension up to gradually increasing total strains at various temperatures, recoverable strains were evaluated and lattice defects left in the microstructure of deformed wires were analyzed by TEM. The recoverable strains evaluated in tensile tests: i) are surprisingly large - exceed 10% strain at low temperatures T ≤ 20 °C, ii) are not significantly restricted by large plastic deformation up to 55% at low temperatures, iii) display local maxima in dependence on total strain in tensile tests at low temperatures, iv) decrease with increasing test temperatures and iv) increase with increasing total strain in tensile tests at high temperatures T ≥ 50 °C. Besides slip dislocations, key lattice defects created by the tensile deformation beyond the martensite yield point are deformation bands containing {114} austenite twins or R-phase. No other austenite twins were found statistically relevant.

Permanent Link: http://hdl.handle.net/11104/0301781