Calculated elastic properties of M2AlC (M=Ti, V, Cr, Nb and Ta)

M2AlC phases, where M is a transition metal, are layered ternary compounds that possess unusual properties. In this paper, we have calculated the elastic properties of M2AlC, with M=Ti, V, Cr, Nb and Ta, by means of ab initio total energy calculations using the projector augmented-wave method. We have derived the bulk and shear moduli, Youngʹs moduli and Poissonʹs ratio for ideal polycrystalline M2AlC aggregates. We have estimated the elastic modulus of Cr2AlC with 357.7 GPa while the values of all other phases are in the range 309±10 GPa. We suggest that this can be understood based on the calculated bond energies for the M–C bonds. Furthermore, our results indicate a profound elastic anisotropy of M2AlC even compared to materials with a well-established anisotropic character such as α-alumina. Finally, we have estimated the Debye temperatures of M2AlC from the average sound velocity.