Effect of oxygen content on microstructure, mechanical properties, and electronic properties of β-Ti3Nb: A first-principles study

β-Ti-Nb alloys have drawn widespread attention on account of their excellent mechanical properties, phase stability, and chemical performance. In this study, first-principles calculations are utilized to examine how the non-metallic element O affects the stability and mechanical characteristics of β-Ti3Nb. The most remarkable result of the change from the lattice constants is that O induces α” phase structure. The computation results of the elastic modulus and phonon spectrum confirm the structural and dynamical stability of all the Ti-Nb-O solid solutions. In addition, the ideal tensile and shear strength in various directions are predicted by simulating tensile and shear deformations. The results indicate that the theoretical strength of β-Ti3Nb is improved when maintaining O concentration within a certain range. Particularly, the 20 at% Ti-Nb-O system shows extraordinary shear strength and tensile strength. Finally, the bonding characteristics of the Ti-Nb-O systems under stress loading are analyzed by electronic structure. The results in this work have great significance for the design and application of Ti-Nb alloys. [Display omitted] •Oxygen additions to β-Ti3Nb produces a remarkable strengthening effect.•The optimized lattice structure of O-doped β-Ti3Nb is similar to α” phase, speculating that O induces α” phase structure.•The tensile strength is the strongest in the [111] direction and the (100) [001] direction is the most prone to slip.•The solid solutions with O content of 20 at.% and 27 at.% possess excellent shear deformation resistance and ductility.