Investigation on the structural, electronic, elastic and mechanical properties of Ti2Al(C1-xOx) solid solutions: First-principles calculations

In the present work, the structural, electronic, elastic and mechanical properties of Ti2AlC and Ti2Al(C1-xOx) solid solutions were investigated using first-principles calculations for varied O content incorporation (x = 0, 0.125, 0.25, 0.375, 0.5). According to the calculation results, all Ti2Al(C1-xOx) solid solutions with various x values are stable, and the bonding strength of the Ti–Al bond increases with the doping of O element. In addition, the shear modulus G and C44 elastic constant of Ti2Al(C1-xOx) solid solutions are both lower than the bulk modulus B, indicating that the phase has good damage tolerance. Not only that, compared with Ti2AlC, the plasticity and toughness of Ti2Al(C1-xOx) solid solutions are improved with the increase of O atom doping and doping ratio. Simultaneously, the doping of O atom is also beneficial to reduce the generalized stacking fault energy of Ti2AlC, making the Ti2Al(C1-xOx) solid solutions more prone to shear deformation, thereby further enhancing plasticity.