Ab initio study of chemical disorder as an effective stabilizing mechanism of bcc-based TiAl(+Mo)

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F68081723%3A_____%2F20%3A00532800" target="_blank" >RIV/68081723:_____/20:00532800 - isvavai.cz</a>

Výsledek na webu

<a href="https://journals.aps.org/prmaterials/abstract/10.1103/PhysRevMaterials.4.103604" target="_blank" >https://journals.aps.org/prmaterials/abstract/10.1103/PhysRevMaterials.4.103604</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1103/PhysRevMaterials.4.103604" target="_blank" >10.1103/PhysRevMaterials.4.103604</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Ab initio study of chemical disorder as an effective stabilizing mechanism of bcc-based TiAl(+Mo)

Popis výsledku v původním jazyce

To shed a new light on the complex microstructural evolution in the Ti–Al–Mo system, we employnab initio calculations to study bcc-fcc structural transformations of ordered βo-TiAl(+Mo) and disorderednβ-TiAl(+Mo) to ordered γ -TiAl(+Mo) and hypothetically assumed disordered γdis-TiAl(+Mo) alloys, respectively.nIn particular, tetragonal (Bain’s path) and trigonal transformations are combined with the concept ofnspecial quasirandom structures (SQS) and examined. Our calculations of the ordered phases show that the βo →nγ tetragonal transformation of TiAl is barrierless, i.e., proceeds spontaneously, reflecting the genuine structuralninstability of the βo phase. Upon alloying of ≈7.4 at.%Mo, a small barrier between βo and γ -related local energynminima is formed. Yet a higher Mo content of ≈9 at.% leads to an opposite-direction barrierless transformationnγ → βo, i.e., fully stabilizing the βo phase. Considering the disordered phases, the β-Ti0.5Al0.5−xMox andnγdis-Ti0.5Al0.5−xMox are energetically very close. Importantly, for all here-considered compositions up to 11 at.%nof Mo, a small energy barrier separates β-TiAl(+Mo) and γdis-TiAl(+Mo) energy minima. Finally, a trigonalnpath was studied as an alternative transformation connecting disordered β and γdis-TiAl phases, but it turns outnthat it exhibits an energy barrier over 60meV/at. which, in comparison to the Bain’s path with 9meV/at. barrier,neffectively disqualifies the trigonal transformation for the TiAl system.

Název v anglickém jazyce

Ab initio study of chemical disorder as an effective stabilizing mechanism of bcc-based TiAl(+Mo)

Popis výsledku anglicky

To shed a new light on the complex microstructural evolution in the Ti–Al–Mo system, we employnab initio calculations to study bcc-fcc structural transformations of ordered βo-TiAl(+Mo) and disorderednβ-TiAl(+Mo) to ordered γ -TiAl(+Mo) and hypothetically assumed disordered γdis-TiAl(+Mo) alloys, respectively.nIn particular, tetragonal (Bain’s path) and trigonal transformations are combined with the concept ofnspecial quasirandom structures (SQS) and examined. Our calculations of the ordered phases show that the βo →nγ tetragonal transformation of TiAl is barrierless, i.e., proceeds spontaneously, reflecting the genuine structuralninstability of the βo phase. Upon alloying of ≈7.4 at.%Mo, a small barrier between βo and γ -related local energynminima is formed. Yet a higher Mo content of ≈9 at.% leads to an opposite-direction barrierless transformationnγ → βo, i.e., fully stabilizing the βo phase. Considering the disordered phases, the β-Ti0.5Al0.5−xMox andnγdis-Ti0.5Al0.5−xMox are energetically very close. Importantly, for all here-considered compositions up to 11 at.%nof Mo, a small energy barrier separates β-TiAl(+Mo) and γdis-TiAl(+Mo) energy minima. Finally, a trigonalnpath was studied as an alternative transformation connecting disordered β and γdis-TiAl phases, but it turns outnthat it exhibits an energy barrier over 60meV/at. which, in comparison to the Bain’s path with 9meV/at. barrier,neffectively disqualifies the trigonal transformation for the TiAl system.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10302 - Condensed matter physics (including formerly solid state physics, supercond.)

Projekt

<a href="/cs/project/LQ1601" target="_blank" >LQ1601: CEITEC 2020</a><br>

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2020

Kód důvěrnosti údajů

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

Název periodika

Physical Review Materials

ISSN

2475-9953

e-ISSN

—

Svazek periodika

4

Číslo periodika v rámci svazku

10

Stát vydavatele periodika

US - Spojené státy americké

Počet stran výsledku

14

Strana od-do

103604

Kód UT WoS článku

000576705800004

EID výsledku v databázi Scopus

2-s2.0-85094142110