First-principles investigations of Fe-based A₃BX ceramics with high stiffness and damage tolerance

In the search for high-stiffness and damage-tolerant materials, Fe-based A₃BX carbide and nitride anti-perovskites were studied using first-principles calculations. These perovskites were found to be stable in cubic structures, as substantiated by the formation energy, elastic Born stability criterion, and phonon dispersion spectrum analysis. The GGA functional was applied for geometry optimization, and the lattice constants are found to be 3.730 Å, 3.715 Å, 3.832 Å, and 3.828 Å for Fe₃AlC, Fe₃AlN, Fe₃SnC, and Fe₃SnN, respectively. Elastic property analysis reveals that all the materials have large elastic moduli, high sound velocities, and high Debye temperatures. Among them, carbides have superior stiffness and quasi-ductile properties, and they can be further improved by applying additional pressure. Preliminary analysis of electronic properties indicates that they are ferromagnetic and metallic compounds. Their high melting temperatures (>2600 K) confirm their potential in high-temperature applications. The lowest thermal conductivity of Fe₃SnN suggests its potential in efficient solid-state refrigeration application. Moreover, Fe₃SnC is proposed to be a viable damage-tolerant material with good prospects. Under 10 GPa external pressure, it possesses a ductile structure with a Young's modulus of 402.15 GPa and bulk modulus of 280.25 GPa.