Investigation of the Precipitation Processes in NiTi Filaments

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F68407700%3A21340%2F18%3A00325109" target="_blank" >RIV/68407700:21340/18:00325109 - isvavai.cz</a>

Výsledek na webu

<a href="http://dx.doi.org/10.1007/978-3-319-76968-4_27" target="_blank" >http://dx.doi.org/10.1007/978-3-319-76968-4_27</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1007/978-3-319-76968-4_27" target="_blank" >10.1007/978-3-319-76968-4_27</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Investigation of the Precipitation Processes in NiTi Filaments

Popis výsledku v původním jazyce

Precipitation in Ni-rich NiTi alloy is an influential process affecting material properties such as fatigue life, tensile strength or thermomechanical response. In this work, a nonconventional method of pulse heating by electric current was employed to recover cold-worked NiTi filaments (50 μm in diameter) and set the initial microstructure without precipitation. The impact of recovery processes and Ni-rich precipitates on mechanical properties can be separated to some extent, owing to the ultrafast electric current annealing. Afterwards, the NiTi filaments were subjected to an aging at 350–520 °C for 2–120 min. The aging at appropriate temperature allows a fluent and predictable adjustment of superelastic response together with an increase in tensile strength of approx. 20%. Small angle neutron scattering experiments were also performed to determine the mean size of Ni-rich precipitates. Less than 10 nm precipitates are created at 350 °C and 2 h aging, which yields a stable superelastic response and higher tensile strength. On the other hand, the filaments annealed at 520 °C show significant instability during superelastic cycling, a decrease in tensile strength and a precipitate mean size that significantly increases up to 500 nm.

Název v anglickém jazyce

Investigation of the Precipitation Processes in NiTi Filaments

Popis výsledku anglicky

Precipitation in Ni-rich NiTi alloy is an influential process affecting material properties such as fatigue life, tensile strength or thermomechanical response. In this work, a nonconventional method of pulse heating by electric current was employed to recover cold-worked NiTi filaments (50 μm in diameter) and set the initial microstructure without precipitation. The impact of recovery processes and Ni-rich precipitates on mechanical properties can be separated to some extent, owing to the ultrafast electric current annealing. Afterwards, the NiTi filaments were subjected to an aging at 350–520 °C for 2–120 min. The aging at appropriate temperature allows a fluent and predictable adjustment of superelastic response together with an increase in tensile strength of approx. 20%. Small angle neutron scattering experiments were also performed to determine the mean size of Ni-rich precipitates. Less than 10 nm precipitates are created at 350 °C and 2 h aging, which yields a stable superelastic response and higher tensile strength. On the other hand, the filaments annealed at 520 °C show significant instability during superelastic cycling, a decrease in tensile strength and a precipitate mean size that significantly increases up to 500 nm.

Druh

D - Stať ve sborníku

CEP obor

—

OECD FORD obor

20501 - Materials engineering

Projekt

—

Návaznosti

S - Specificky vyzkum na vysokych skolach

Rok uplatnění

2018

Kód důvěrnosti údajů

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

Název statě ve sborníku

Proceedings of the International Conference on Martensitic Transformations: Chicago

ISBN

978-3-319-76967-7

ISSN

2367-1181

e-ISSN

—

Počet stran výsledku

5

Strana od-do

173-177

Název nakladatele

Springer

Místo vydání

Basel

Místo konání akce

Hyatt Regency, Chicago, Illinois

Datum konání akce

9. 7. 2017

Typ akce podle státní příslušnosti

WRD - Celosvětová akce

Kód UT WoS článku

—