First-principles study of impurity diffusion coefficients in Niobium

Nb based alloys have potential applications in aerospace due to their good high temperature strength and low temperature plasticity. It is very important to study the atomic diffusion properties for understanding the dynamic process of Nb-based alloys. However, the diffusion data of some elements in Nb are still unknown. In the present work, the impurity diffusion coefficients of ten different elements (Si, Ti, V, Ta, Ru, Cr, Te, Tc, Ir, and Y) in BCC Nb was studied by first-principles calculation based on density functional theory and nine frequency model. The climbing image nudged elastic band (CI-NEB) method was used to find the minimum energy path and the related saddle point structure during diffusion. The atomic jump frequency was calculated through the Vineyard’ s transition state theory. The results are consistent well with the exiting experimental and previous calculation results.