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

J 2020

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

ABDOSHAHI, Neda; Petra SPOERK-ERDELY; Martin FRIAK; Svea MAYER; Mojmír ŠOB et. al.

Basic information

Original name

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

Authors

ABDOSHAHI, Neda; Petra SPOERK-ERDELY; Martin FRIAK; Svea MAYER; Mojmír ŠOB (203 Czech Republic, guarantor, belonging to the institution) and David HOLEC

Edition

Physical Review Materials, College Park, Maryland, American Physical Society, 2020, 2475-9953

Other information

Language

English

Type of outcome

Article in a journal

Field of Study

10302 Condensed matter physics

Country of publisher

United States of America

Confidentiality degree

is not subject to a state or trade secret

References:

URL

Impact factor

Impact factor: 3.989

RIV identification code

RIV/00216224:14310/20:00117220

Organization unit

Faculty of Science

DOI

https://doi.org/10.1103/PhysRevMaterials.4.103604

UT WoS

000576705800004

EID Scopus

2-s2.0-85094142110

Keywords in English

First-principles calculations; Phase transitions by order

Abstract

In the original language

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.

Links

LM2015085, research and development project

Name: CERIT Scientific Cloud (Acronym: CERIT-SC)

Investor: Ministry of Education, Youth and Sports of the CR, CERIT Scientific Cloud

LM2018140, research and development project

Name: e-Infrastruktura CZ (Acronym: e-INFRA CZ)

Investor: Ministry of Education, Youth and Sports of the CR

LQ1601, research and development project

Name: CEITEC 2020 (Acronym: CEITEC2020)

Investor: Ministry of Education, Youth and Sports of the CR

90042, large research infrastructures

Name: CESNET II

Cite

ABDOSHAHI, Neda; Petra SPOERK-ERDELY; Martin FRIAK; Svea MAYER; Mojmír ŠOB and David HOLEC. Ab initio study of chemical disorder as an effective stabilizing mechanism of bcc-based TiAl( plus Mo). Physical Review Materials. College Park, Maryland: American Physical Society, 2020, vol. 4, No 10, p. 1-14. ISSN 2475-9953. Available from: https://doi.org/10.1103/PhysRevMaterials.4.103604.

@article{1703497,
   author = {Abdoshahi, Neda and SpoerkandErdely, Petra and Friak, Martin and Mayer, Svea and Šob, Mojmír and Holec, David},
   article_location = {College Park, Maryland},
   article_number = {10},
   doi = {https://doi.org/10.1103/PhysRevMaterials.4.103604},
   keywords = {First-principles calculations; Phase transitions by order},
   language = {eng},
   issn = {2475-9953},
   journal = {Physical Review Materials},
   title = {Ab initio study of chemical disorder as an effective stabilizing mechanism of bcc-based TiAl( plus Mo)},
   url = {https://doi.org/10.1103/PhysRevMaterials.4.103604},
   volume = {4},
   year = {2020}
}

TY  - JOUR
ID  - 1703497
AU  - Abdoshahi, Neda - Spoerk-Erdely, Petra - Friak, Martin - Mayer, Svea - Šob, Mojmír - Holec, David
PY  - 2020
TI  - Ab initio study of chemical disorder as an effective stabilizing mechanism of bcc-based TiAl( plus Mo)
JF  - Physical Review Materials
VL  - 4
IS  - 10
SP  - 1-14
EP  - 1-14
PB  - American Physical Society
SN  - 24759953
KW  - First-principles calculations
KW  - Phase transitions by order
UR  - https://doi.org/10.1103/PhysRevMaterials.4.103604
L2  - https://doi.org/10.1103/PhysRevMaterials.4.103604
N2  - 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.
ER  -

ABDOSHAHI, Neda; Petra SPOERK-ERDELY; Martin FRIAK; Svea MAYER; Mojmír ŠOB and David HOLEC. Ab initio study of chemical disorder as an effective stabilizing mechanism of bcc-based TiAl( plus Mo). \textit{Physical Review Materials}. College Park, Maryland: American Physical Society, 2020, vol.~4, No~10, p.~1-14. ISSN~2475-9953. Available from: https://doi.org/10.1103/PhysRevMaterials.4.103604.

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