Lattice Defects Generated by Cyclic Thermomechanical Loading of Superelastic NiTi Wire

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F61389005%3A_____%2F21%3A00541796" target="_blank" >RIV/61389005:_____/21:00541796 - isvavai.cz</a>

Nalezeny alternativní kódy

RIV/68378271:_____/21:00563592 RIV/68407700:21340/21:00362709

Výsledek na webu

<a href="https://doi.org/10.1007/s40830-021-00315-4" target="_blank" >https://doi.org/10.1007/s40830-021-00315-4</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1007/s40830-021-00315-4" target="_blank" >10.1007/s40830-021-00315-4</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Lattice Defects Generated by Cyclic Thermomechanical Loading of Superelastic NiTi Wire

Popis výsledku v původním jazyce

Cyclic instability of stress-strain-temperature functional responses of NiTi is presumably due to the plastic deformation accompanying martensitic transformation proceeding under external stress. In order to obtain systematic experimental evidence on this, we have performed series of cyclic thermomechanical loading tests (10 cycles) on superelastic NiTi wires with nanocrystalline microstructure, evaluated accumulated unrecovered strains and analysed permanent lattice defects created during the cycling by TEM. The accumulated unrecovered strains and density of lattice defects increased with increasing temperature and stress, at which the forward and/or reverse transformation proceeded. It did not correlate with the temperature and stress applied in the test as such. If the martensitic transformation proceeded at low stress (<100 MPa), the cyclic stress-strain-temperature responses of the wire were found to be almost stable (only marginal accumulated unrecovered strain and few isolated dislocation loops and segments were generated during the thermomechanical cycling). This was the case in thermal cycling at low stresses or in cyclic shape memory test. If the forward and/or reverse martensitic transformation proceeded under large external stress (>250 MPa), the responses were very unstable (large accumulated unrecovered strains and high density of dislocations and deformation bands). A scheme allowing for estimating the cyclic instability of functional behaviours of various NiTi wires in wide range of thermomechanical loading tests was introduced.

Název v anglickém jazyce

Lattice Defects Generated by Cyclic Thermomechanical Loading of Superelastic NiTi Wire

Popis výsledku anglicky

Cyclic instability of stress-strain-temperature functional responses of NiTi is presumably due to the plastic deformation accompanying martensitic transformation proceeding under external stress. In order to obtain systematic experimental evidence on this, we have performed series of cyclic thermomechanical loading tests (10 cycles) on superelastic NiTi wires with nanocrystalline microstructure, evaluated accumulated unrecovered strains and analysed permanent lattice defects created during the cycling by TEM. The accumulated unrecovered strains and density of lattice defects increased with increasing temperature and stress, at which the forward and/or reverse transformation proceeded. It did not correlate with the temperature and stress applied in the test as such. If the martensitic transformation proceeded at low stress (<100 MPa), the cyclic stress-strain-temperature responses of the wire were found to be almost stable (only marginal accumulated unrecovered strain and few isolated dislocation loops and segments were generated during the thermomechanical cycling). This was the case in thermal cycling at low stresses or in cyclic shape memory test. If the forward and/or reverse martensitic transformation proceeded under large external stress (>250 MPa), the responses were very unstable (large accumulated unrecovered strains and high density of dislocations and deformation bands). A scheme allowing for estimating the cyclic instability of functional behaviours of various NiTi wires in wide range of thermomechanical loading tests was introduced.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

20501 - Materials engineering

Projekt

Výsledek vznikl pri realizaci vícero projektů. Více informací v záložce Projekty.

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2021

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Shape Memory and Superelasticity

ISSN

2199-384X

e-ISSN

2199-3858

Svazek periodika

7

Číslo periodika v rámci svazku

MAR

Stát vydavatele periodika

CH - Švýcarská konfederace

Počet stran výsledku

24

Strana od-do

65-88

Kód UT WoS článku

000634670200002

EID výsledku v databázi Scopus

2-s2.0-85103429720