Experimental and theoretical study on electronic structure and mechanical property of TaxHf1−xC

Abstract TaxHf1−xC can withstand extreme environments, but the challenges in their densification prevent them from being used for many applications. In this paper, a method to prepare dense homogeneous TaxHf1−xC solid solutions with a cubic structure is prosed. Moreover, mechanical properties of TaxHf1−xC are characterized, including the elastic modulus and Poisson ratio. The hardness and Debye temperature are estimated by using empirical equation. The properties related to the electronic structures of TaxHf1−xC (x = 0, 0.25, 0.5, 0.75, 1), including the density of states and Mulliken populations, are systematically calculated by using the first-principles method. From the calculation, we found that all TaxHf1−xC are thermodynamically stable at room temperature. Moreover, Ta0.5Hf0.5C has a higher Young's modulus and shear modulus comparing to Ta0.75Hf0.25C and Ta0.25Hf0.75C. Ta0.75Hf0.25C possesses the highest bulk modulus, suggesting that it has greater comprehensive mechanical properties than the others. In addition, the compositions of their chemical bonds are discussed according to their density of states, population analysis and Debye temperature. We found that the number of valence electrons of transition metals significantly affects their mechanical properties. Finally, the relation between the mechanical properties of TaxHf1−xC (x = 0, 0.25, 0.5, 0.75, 1) and the chemical bonds are summarized.