Theoretical investigation the effect of A-site elements on mechanical and thermal properties in Ti2AC (A = Al, Ga, In, Si, Ge, Sn) compounds

To better understanding the effect of group-A atoms on the properties in Ti2AC (A = Al, Ga, In, Si, Ge, Sn) compounds, the phase stability, elastic properties, electronic structures and thermal properties of the compounds were calculated using density functional theory (DFT). The results revealed that the A-site elements affect largely the lattice constant c than the lattice constant a. The compounds are thermodynamically and mechanically stable. Ti2SiC has higher bulk modulus with 163.7 GPa, which makes it has higher compression resistance among the Ti2AC family. Ti2InC has the lowest hardness because of it has the smallest shear modulus (103.8 GPa) and C44 (95.1 GPa) among the Ti2AC family. The chemical bond of all compounds is a combination of metallic and covalent bonds characteristic. In addition, Ti2AlC has the largest Debye temperature of 751.5 K, while Ti2InC and Ti2SnC possess the smallest value of 546.9 K, which indicate that Ti2InC and Ti2SnC compounds are potential materials for thermal barrier coating (TBC) applications. This work will provide a valuable theoretical basis for further study of Ti2AC ternary carbides with excellent mechanical and thermal properties.