Experimental and theoretical study on electronic structure and mechanical property of Ta_xHf_1−xC

Ta_xHf_1−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 Ta_xHf_1−xC solid solutions with a cubic structure is prosed. Moreover, mechanical properties of Ta_xHf_1−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 Ta_xHf_1−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 Ta_xHf_1−xC are thermodynamically stable at room temperature. Moreover, Ta_0.5Hf_0.5C has a higher Young's modulus and shear modulus comparing to Ta_0.75Hf_0.25C and Ta_0.25Hf_0.75C. Ta_0.75Hf_0.25C 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 Ta_xHf_1−xC (x = 0, 0.25, 0.5, 0.75, 1) and the chemical bonds are summarized.