Evolution of the structure and properties of (Zr1-xHfx)B2 solid solution ceramics from first-principle theory

As typical ultra-high temperature ceramics, both ZrB2 and HfB2 have unique properties such as excellent mechanical performance and oxidation resistance, are promising candidates for the aerospace industry. In this work, the phase stability, electronic, mechanical and thermodynamic properties of (Zr1-xHfx)B2 solid solution ceramics were systematically studied performing by first-principles calculations. The calculated results of structural optimization and elastic constants are in good agreement with the experimental values, which confirms the reliability of the proposed model. The lattice parameters of the optimized (Zr1-xHfx)B2 solid solution ceramics are linearly related to the Hf content, while a decrease is detected as the increasing Hf content. The calculated elastic constants show that the addition of Hf is beneficial in improving the mechanical properties of the (Zr1-xHfx)B2 solid solution, including the elastic modulus, hardness and fracture toughness. In addition, the (Zr1-xHfx)B2 solid solution was found to be kinetically stable. From the trend of the calculated value of the Debye temperature, it can be found that the addition of Hf can effectively reduce the thermal conductivity of solid solution materials. Our work introduced an important theoretical framework, which is of great significance for the development of solid solution diboride material systems with adjustable composition and properties.

Automated summary

In this work, the properties of (Zr1-xHfx)B2 solid solution ceramics were studied using first-principles calculations. It was found that the addition of Hf can improve the mechanical properties and thermal conductivity of the ceramics, and the solid solution materials exhibit kinetic stability. This work provides an important theoretical framework for the development of solid solution diboride material systems with adjustable composition and properties.