Publication detail

Mechanical stability of Ni and Ir under hydrostatic and uniaxial loading

ŘEHÁK, P. ČERNÝ, M. ŠOB, M.

Czech title

Mechanická stabilita Ni a Ir za podmínek hydrostatického a jednoosého zatížení

English title

Mechanical stability of Ni and Ir under hydrostatic and uniaxial loading

Type

journal article in Web of Science

Language

en

Original abstract

Two fcc crystals, Ni and Ir, are subjected to simulated isotropic and uniaxial tension along the 100 direction. Their structural stability is assessed by analyzing phonon spectra that are calculated from first principles for different values of strain. A relevant analysis of elastic stability conditions is also performed. Predicted elastic instabilities correspond well to those associated with soft phonons with vanishing wavevectors. Although most of previous studies predicted that first instabilities in crystals correspond to macroscopic (elastic) instabilities, we found soft phonons of finite wavevectors at lower strains (and stresses) during both considered loadings in the crystal of Ir. Predicted instabilities were confirmed by our models of microscopic deformation.

Czech abstract

Dva FCC krystaly, Ni a Ir, se podrobí simulovanému izotropního a jednoosým tahem podél <100> směr. Jejich strukturální stabilita je hodnocena analýzou fononová spektra, které jsou vypočtené z prvních principů pro různé hodnoty napětí.Příslušná analýza elastických podmínek stability se rovněž provádí. Předpokládané elastické nestability odpovídají i těm spojeným s měkkými fononů s mizením wavevectors. Ačkoli většina z předchozích studií předpověděl, že první nestability v krystalech odpovídají makroskopických (elastické) nestabilit, jsme zjistili měkké fononů z konečných wavevectors na nižších kmenů (a napětí) během obou uvažovaných zatížení v krystalu Ir. Předpokládané nestability byly potvrzeny našich modelů mikroskopického deformace.

English abstract

Two fcc crystals, Ni and Ir, are subjected to simulated isotropic and uniaxial tension along the 100 direction. Their structural stability is assessed by analyzing phonon spectra that are calculated from first principles for different values of strain. A relevant analysis of elastic stability conditions is also performed. Predicted elastic instabilities correspond well to those associated with soft phonons with vanishing wavevectors. Although most of previous studies predicted that first instabilities in crystals correspond to macroscopic (elastic) instabilities, we found soft phonons of finite wavevectors at lower strains (and stresses) during both considered loadings in the crystal of Ir. Predicted instabilities were confirmed by our models of microscopic deformation.

Keywords in English

ab initio calculations, elastic stability, phonon instability, theoretical strength, hydrostatic loading, uniaxial loading

RIV year

2015

Released

28.05.2015

Publisher

IOP Publishing Ltd.

Location

Bristol

ISSN

0965-0393

Volume

23

Number

5

Pages from–to

1–10

Pages count

10

BIBTEX


@article{BUT114652,
  author="Petr {Řehák} and Miroslav {Černý} and Mojmír {Šob},
  title="Mechanical stability of Ni and Ir under hydrostatic and uniaxial loading",
  year="2015",
  volume="23",
  number="5",
  month="May",
  pages="1--10",
  publisher="IOP Publishing Ltd.",
  address="Bristol",
  issn="0965-0393"
}