First-principles calculations to investigate mechanical and thermodynamics properties of multi-anion oxycarbonitride ceramics TiCNO and TiZrCNO

Abstract

Multicomponent ceramics have attracted increasingly attention due to their potential applications. Employing density functional theory (DFT) and the special quasi-random structure (SQS), the structural stability and elastic characteristics of TiCNO and TiZrCNO are systematically explored in this study. The available experimental data and the optimized lattice parameters coincide very well. Both high entropy oxycarbonitrides are thermodynamically stable because the formation enthalpies are negative. According to the present results of elastic parameters, the slight expense of the strength and stiffness the ductility is improved. The increase of ductility presumably originates from the multicomponent mixing in the anion sublattice, the subsequent incorporation of Zr results in the stronger influence due to the more severe lattice distortion, as discussed in our previous study. The anisotropy of two ceramics are studied systematically, the role of the anisotropy is explored in wear/cutting applications. Then the thermodynamic properties of the two ceramics are also studied further applying Debye-Grüneisen model. Thermodynamic properties of two materials exhibit essentially similar trends as temperature rises. Because the larger lattice distortion by the subsequent addition of Zr, the bulk moduli and thermal expansion coefficient for TiZrCNO change slowly with temperature. Clearly the influences of the multianion mixing, especially the contribution from the following incorporation of Zr which leads to larger internal distortion should pay high attention. The current investigations provide valuable insight into the mechanical and thermodynamic behavior of these two multicomponent ceramics.