### Abstract

The temperature-dependent structural properties and anisotropic thermal expansion coefficients of α-/β-Nb_{5}Si_{3} 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-Nb_{5}Si_{3} phase is much more temperature dependence than that of β-Nb_{5}Si_{3} phase. The total/partial density of states of α-/β-Nb_{5}Si _{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 _{5}Si_{3} 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-Nb_{5}Si_{3} phase possesses a superior ability of compression resistance but an inferior ability of higherature resistance of mechanical properties than those of β-Nb _{5}Si_{3} phase. The bonding features of α-/β- Nb_{5}Si_{3} 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 language | English (US) |
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Pages (from-to) | 72-79 |

Number of pages | 8 |

Journal | Intermetallics |

Volume | 46 |

DOIs | |

State | Published - 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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## Cite this

_{5}Si

_{3}phases from first-principles calculations.

*Intermetallics*,

*46*, 72-79. https://doi.org/10.1016/j.intermet.2013.10.027