First-principles study on doping effect of B in NbSi2 with C40 structure.

The influence of B element on structure and mechanical properties of NbSi 2 is investigated by using the first-principles approach. To explore the solution strengthening mechanism of B element, the doped sites including the octahedral interstice site (OI) and tetrahedral interstice site (TI) are considered. It is found that B element prefers to occupy the OI site in comparison with the TI site. B element occupied OI site can slightly improve the volume deformation resistance for NbSi 2 . Importantly, B element leads to brittle-to-ductile transition. The reason is that the addition of B element can weaken the charge interaction between the Nb and Si atoms. [ABSTRACT FROM AUTHOR]