Strain effect on the defect formation and diffusion in Ti2AlC and Ti3AlC2: A first-principles study

•The process of Al atom diffusing to the Ti vacancy is energetically favorable when compared with itself staying at its original position.•The cross-layer atomic diffusion in MAX phase materials can be slowed down under the compressive strain along the ab axes.•As the imposed equibiaxial in-plane strain goes from compressive to tensile states, the formation energies of Ti and C vacancies increase, while the formation energy of Al vacancy decreases.