First-principles study of the ideal cleavage fracture of Cr2Nb microalloyed by X (Al, Ni, Co, Ti)

The structural properties and elastic constants of the pure Cr2Nb, the ideal cleavage fracture properties of the Cr2Nb with the elements X (Al, Ni, Co and Ti) and site preference of the elements X were investigated using the first-principles method. Our calculated lattice parameters and elastic constants of the pure Cr2Nb are in agreement with the experimental data. Moreover, our calculated results show that the elements X (Al, Ni and Co) occupy the Cr site, and Ti the Nb site in Cr2Nb. The cleavage energies Gc and critical cleavage stress σc with and without the additive elements in the cleavage planes were calculated. The results demonstrate that the elements X (Al, Ni, Co and Ti) could be used to improve the cleavage properties of Cr2Nb. Finally, the electronic mechanism behind the effects of the additive elements on the ideal cleavage properties of Cr2Nb was investigated by calculating the electronic structure.