Impact of hydrogen-assisted heat treatments on microstructure and transformation path in a Ni-rich NiTi shape memory alloy

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216224%3A14310%2F13%3A00107100" target="_blank" >RIV/00216224:14310/13:00107100 - isvavai.cz</a>

Nalezeny alternativní kódy

RIV/68081723:_____/13:00421756

Výsledek na webu

<a href="https://www.sciencedirect.com/science/article/pii/S0925838812013138" target="_blank" >https://www.sciencedirect.com/science/article/pii/S0925838812013138</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1016/j.jallcom.2012.07.096" target="_blank" >10.1016/j.jallcom.2012.07.096</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Impact of hydrogen-assisted heat treatments on microstructure and transformation path in a Ni-rich NiTi shape memory alloy

Popis výsledku v původním jazyce

We report results of differential scanning calorimetry and transmission electron microscopy experiments in which martensitic transformations and microstructure of Ti-50.9 at%Ni shape memory samples were investigated after heat treatments in controlled gaseous environments. The heat treatments were performed in mixtures consisting of hydrogen and helium with an overall pressure of 900 mbar. The cylindrical samples were heat treated either in a Regime I (850 degrees C/1800 s/WQ) or in a Regime II (the Regime I plus 450 degrees C/3600 s/WQ). DSC charts clearly document that the B2 -&gt; B19' or R -&gt; B19' martensitic phase transitions diminish after Regime I and Regime II treatments with increasing partial pressure of hydrogen. We show that the hydrogen rich environments do not cause variations in size and density of Ni4Ti3 particles. Conversely, the Regime I heat treatments assisted by hydrogen result in 1/2 (111)(B2) diffuse intensity maxima in selected area electron diffraction patterns. These maxima were not observed after heat treatments in hydrogen deficient atmospheres. Therefore, we suggest that the gradual suppression of the martensitic transformation may be related to either chemical and/or strain modulations of the B2 lattice triggered by the presence of interstitial hydrogen atoms.

Název v anglickém jazyce

Impact of hydrogen-assisted heat treatments on microstructure and transformation path in a Ni-rich NiTi shape memory alloy

Popis výsledku anglicky

We report results of differential scanning calorimetry and transmission electron microscopy experiments in which martensitic transformations and microstructure of Ti-50.9 at%Ni shape memory samples were investigated after heat treatments in controlled gaseous environments. The heat treatments were performed in mixtures consisting of hydrogen and helium with an overall pressure of 900 mbar. The cylindrical samples were heat treated either in a Regime I (850 degrees C/1800 s/WQ) or in a Regime II (the Regime I plus 450 degrees C/3600 s/WQ). DSC charts clearly document that the B2 -&gt; B19' or R -&gt; B19' martensitic phase transitions diminish after Regime I and Regime II treatments with increasing partial pressure of hydrogen. We show that the hydrogen rich environments do not cause variations in size and density of Ni4Ti3 particles. Conversely, the Regime I heat treatments assisted by hydrogen result in 1/2 (111)(B2) diffuse intensity maxima in selected area electron diffraction patterns. These maxima were not observed after heat treatments in hydrogen deficient atmospheres. Therefore, we suggest that the gradual suppression of the martensitic transformation may be related to either chemical and/or strain modulations of the B2 lattice triggered by the presence of interstitial hydrogen atoms.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

20501 - Materials engineering

Projekt

—

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2013

Kód důvěrnosti údajů

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

Název periodika

Journal of Alloys and Compounds

ISSN

0925-8388

e-ISSN

1873-4669

Svazek periodika

577

Číslo periodika v rámci svazku

NOV

Stát vydavatele periodika

CH - Švýcarská konfederace

Počet stran výsledku

4

Strana od-do

„S287“-„S290“

Kód UT WoS článku

000329891400061

EID výsledku v databázi Scopus

2-s2.0-84891629493