Ab initio study of chemical disorder as an effective stabilizing mechanism of bcc-based TiAl( plus Mo)
The result's identifiers
Result code in IS VaVaI
<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216224%3A14310%2F20%3A00117220" target="_blank" >RIV/00216224:14310/20:00117220 - isvavai.cz</a>
Result on the web
<a href="https://doi.org/10.1103/PhysRevMaterials.4.103604" target="_blank" >https://doi.org/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>
Alternative languages
Result language
angličtina
Original language name
Ab initio study of chemical disorder as an effective stabilizing mechanism of bcc-based TiAl( plus Mo)
Original language description
To shed a new light on the complex microstructural evolution in the Ti-Al-Mo system, we employ ab initio calculations to study bcc-fcc structural transformations of ordered beta(o)-TiAl(+Mo) and disordered beta-TiAl(+Mo) to ordered gamma-TiAl(+Mo) and hypothetically assumed disordered gamma(dis)-TiAl(+Mo) alloys, respectively. In particular, tetragonal (Bain's path) and trigonal transformations are combined with the concept of special quasirandom structures (SQS) and examined. Our calculations of the ordered phases show that the beta(o )-> gamma tetragonal transformation of TiAl is barrierless, i.e., proceeds spontaneously, reflecting the genuine structural instability of the beta(o) phase. Upon alloying of approximate to 7.4 at.% Mo, a small barrier between beta(o) and gamma-related local energy minima is formed. Yet a higher Mo content of approximate to 9 at.% leads to an opposite-direction barrierless transformation gamma -> beta(o )i.e., fully stabilizing the beta(o) phase. Considering the disordered phases, the beta(o)-Ti0.5Al0.5-xMox and gamma(dis)-Ti0.5Al0.5-xMox, are energetically very close. Importantly, for all here-considered compositions up to 11 at.% of Mo, a small energy barrier separates beta-TiAl(+Mo) and gamma(dis)-TiAl(+Mo) energy minima Finally, a trigonal path was studied as an alternative transformation connecting disordered beta and gamma(dis)-TiAl phases, but it turns out that it exhibits an energy barrier over 60 meV/at. which, in comparison to the Bain's path with 9 meV/at. barrier, effectively disqualifies the trigonal transformation for the TiAl system.
Czech name
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Czech description
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Classification
Type
J<sub>imp</sub> - Article in a specialist periodical, which is included in the Web of Science database
CEP classification
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OECD FORD branch
10302 - Condensed matter physics (including formerly solid state physics, supercond.)
Result continuities
Project
Result was created during the realization of more than one project. More information in the Projects tab.
Continuities
P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)<br>I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace
Others
Publication year
2020
Confidentiality
S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů
Data specific for result type
Name of the periodical
Physical Review Materials
ISSN
2475-9953
e-ISSN
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Volume of the periodical
4
Issue of the periodical within the volume
10
Country of publishing house
US - UNITED STATES
Number of pages
14
Pages from-to
1-14
UT code for WoS article
000576705800004
EID of the result in the Scopus database
2-s2.0-85094142110