Insight into the vacancy effects on mechanical and electronic properties of V₅Si₃ silicides from first-principles...

As so far, the development and application prospects of transition metal silicon-based materials have received the considerable attention. V-Si silicides are one of the most important silicon-based high-temperature materials. Brittle behavior hinders their wide application. In present work, the influence of vackancies on mechanical properties, brittle/ductile behavior and electronic properties of V₅Si₃ silicides is studied using the first-principles calculations. The vacancy formation energy, elastic constants, elastic modulus, brittle/ductile behavior and electronic behavior of the perfect V₅Si₃ and V₅Si₃ with vacancies were comparatively calculated and discussed, respectively. The thermodynamic data and phonon frequencies demonstrate that the V₅Si₃ with different vacancies can exhibit the structural stability. Although the vacancies weaken the hardness of V₅Si₃, the vacancies improve the brittle behavior of the parent V₅Si₃. Especially, the Si_-Va1 and Si_-Va2 vacancies in V₅Si₃ induced brittle-to-ductile transition for V₅Si₃ desilicides. The electronic structures explain the mechanism of the difference of mechanical properties for different vacancies.