Insights into the ultra-high temperature solid solutions Hf-Ta-C-N quaternary system using high-throughput calculation

Abstract

We investigated the structure, elastic, and thermodynamic properties of Hf-Ta-C-N solid solutions using high-throughput density functional theory calculations. The results of the elastic and mechanical properties indicate that increasing the nitrogen content increases the ductility of solid solutions; it also increases the elastic moduli of solid solutions in a specific range of nitrogen contents. The results indicate that the ternary and quaternary solid solutions of the Hf-Ta-C-N system have excellent formability, elastic, and thermal properties. In addition, thermodynamic analyses were performed to obtain temperature-dependent stable phase diagrams of the Hf-Ta-C-N quaternary system. This investigation was performed to determine the suitability of Hf-Ta-C-N quaternary solid solutions in high temperature condition, which was veiled in previous studies. In total, 51 related phases were studied, including 16 solid solutions and four elemental phases (Hf, Ta, C, and N2(g)). Our results indicate that the nitrogen-rich solid solutions can appear even at room temperature. The solid solutions covered a large area of the Hf-Ta-C-N phase spaces, regardless of temperature. As the temperature increases, the stable phase shifts from Ta and N to the Hf and C rich phases.

Keywords

• Transition metal carbonitride
• Ultra-high temperature ceramics
• Ab initio calculation
• Mechanical properties
• Thermal properties
• High-throughput calculation