Abstract

The mechanisms of the Ti and Si self-diffusion in the Ti5Si3 compound are investigated by using the projector augmented-wave method within the density functional theory. The migration and activation energies for Ti and Si atoms were calculated for both vacancy and interstitial mechanisms. It is shown that the smallest migration energy of Ti atom corresponds to the interstitial mechanism, whereas it is by 0.08 eV lower for the Si own-sublattice mechanism than for interstitial one. The concentration of initial point defects within canonical formalism is calculated and the most preferred defects are determined. The temperature-dependent self-diffusion coefficients along two crystallographic directions are calculated. It is shown that Ti atom diffuses faster than Si one. The influence of metals of IVB–VIIB groups on the Ti migration energy is estimated. It is shown that almost all considered impurities increase the migration energy and can lead to a decrease in Ti diffusivity in Ti5Si3.

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