Temperature-dependent mechanical properties of alpha-/beta-Nb 5Si3 phases from first-principles calculations

Weiwei Xu, Jiajia Han, Cuiping Wang, Yi Zhou, Yi Wang, Yongwang Kang, Bin Wen, Xingjun Liu, Zi-kui Liu

Research output: Contribution to journalArticle

19 Scopus citations

Abstract

The temperature-dependent structural properties and anisotropic thermal expansion coefficients of α-/β-Nb5Si3 phases have been determined by minimizing the non-equilibrium Gibbs free energy as functions of crystallographic deformations. The results indicate that the crystal anisotropy of α-Nb5Si3 phase is much more temperature dependence than that of β-Nb5Si3 phase. The total/partial density of states of α-/β-Nb5Si 3 phases are discussed in detail to analyze their electronic hybridizations. It is demonstrated that the bonding of the two phases is mainly contributed from the hybridization between Nb-4d and Si-3p electronic states. The temperature-dependent mechanical properties of α-/β-Nb 5Si3 phases are further investigated via the quasi-harmonic approximation method in coupling with continuum elasticity theory. The calculated single-crystalline and polycrystalline elasticity shows that both phases are mechanically stable and exhibit the intrinsic brittleness. The results also suggest that α-Nb5Si3 phase possesses a superior ability of compression resistance but an inferior ability of higherature resistance of mechanical properties than those of β-Nb 5Si3 phase. The bonding features of α-/β- Nb5Si3 phases are discussed by means of charge density difference analysis in order to explain the difference of the temperature-dependent mechanical properties between the two phases.

Original languageEnglish (US)
Pages (from-to)72-79
Number of pages8
JournalIntermetallics
Volume46
DOIs
StatePublished - Jan 1 2014

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Mechanics of Materials
  • Mechanical Engineering
  • Metals and Alloys
  • Materials Chemistry

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