Theoretical prediction of the influence of defects and atomic occupation on the elastic and electronic properties of NbSi2 form the first-principles calculations

Abstract

In now days, the transition metal silicides are one of the promising materials for making high-temperature materials. To improve the inherent brittleness of the transition metal silicides, the elastic and electronic properties of the C40-type NbSi2 disilicides have been predicted using first-principles calculations. Six defect models (V-Va, Si-Va, N-V, N-Si, O-V, O-Si) were chosen to evaluate the elastic properties of transition metal silicides. According to the data of thermodynamic parameters, NbSi2 with the different defect and doping models shows the phase stability. The introduction of different defects and doping models changes the mechanical behavior. The defect and doping models lead to the decrease in the deformation resistance and hardness of the perfect NbSi2. Additionally, the defect and doping models result in the perfect NbSi2 to actualize the brittle-to-ductile transition. The Nb defects resulted in NbSi2 having the greatest degree of anisotropy. The electronic structures are calculated to discuss the brittle-to- ductile transition for NbSi2 with defects.