The elastic coefficients and mechanical properties (bulk modulus, shear modulus, Young's modulus and Poisson's ratio) of Ti2Al(CxN1−x) continuous solid solutions for x from 0 to 1 are calculated using ab initio DFT methods on 4×4×1 supercell models. It is shown that the properties of these solid solutions do not vary linearly with x. Although the lattice constant c is almost constant for x≤0.5, a increases linearly. For x>0.5, c starts to increase with x while the rate of increase in a slows down. For x between 0.5 and 0.85, the elastic coefficients and the mechanical parameters show interesting dependence on x and crossovers, signifying the complex interplay in the structure and properties in Ti2Al(CxN1−x) solid solutions. The nonlinear variations in mechanical properties are explained in terms of subtle difference in the electronic structure and bonding between nitrides and carbides in complex MAX phase compounds.
Sitaram Aryal, Ridwan Sakidja, Lizhi Ouyang, Wai-Yim Ching, "Elastic and electronic properties of Ti2Al(CxN1−x) solid solutions", Journal of the European Ceramic Society, Volume 35, Issue 12, 2015, Pages 3219-3227, ISSN 0955-2219, https://doi.org/10.1016/j.jeurceramsoc.2015.03.023.