Crystal structure and theoretical elastic property of two new ternary ceramics Hf_3Al_C_6 and Hf_2Al_4C_5

摘要

Two new ternary aluminum carbides, Hf_3Al_4C_6 and Hf_2Al_4C_5, were identified and their crystal structure was determined by a combination of X-ray diffraction, Z-contrast scanning transmission electron microscopy and density-function calculations. Theoretical second-order elastic constants, bulk modulus, shear modulus and Young's modulus of Hf_3Al_4C_6 and Hf_2Al_4C_5, as well as Hf_3Al_3C_5, Hf_2Al_3C_4, HfC and Al_4C_3, were calculated and compared. These new carbides show promisingly high elastic stiffness.