Effects of chromium on structure and mechanical properties of vanadium： A first-principles study
摘要
Stability and diffusion of chromium(Cr) in vanadium(V),the interaction of Cr with vacancies,and the ideal mechanical properties of V are investigated by first-principles calculations.A single Cr atom is energetically favored in the substitution site.Vacancy plays a key role in the trapping of Cr in V.A very strong binding exists between a single Cr atom and the vacancy with a binding energy of 5.03 eV.The first-principles computational tensile test(FPCTT) shows that the ideal tensile strength is 19.1 GPa at the strain of 18% along the [100] direction for the ideal V single crystal,while it decreases to 16.4 GPa at a strain of 12% when one impurity Cr atom is introduced in a 128-atom V supercell.For shear deformation along the most preferable {110} ?111? slip system in V,we found that one substitutional Cr atom can decrease the cleavage energy(γcl) and simultaneously increase the unstable stacking fault energy(γus) in comparison with the ideal V case.The reduced ratio of γcl/γus in comparison with pure V suggests that the presence of Cr can decrease the ductility of V.