Experimental study of covalent Cr3C2 with high ionicity: Sound velocities, elasticity, and mechanical properties under high pressure

The widespread industrial applications of binary transition metal carbides (TMCs) are closely related to their complex chemical bonds. Owing to the high number of ionic components of chromium carbide (Cr3C2), it is a challenge to accurately estimate its elasticity and mechanical properties. Pure polycrystalline Cr3C2 was synthesized via high pressure and high temperature method, and its sound velocities, elasticity, and mechanical properties were investigated using high-pressure ultrasonic interferometry combined with density functional theory calculations. Furthermore, its bulk modulus, shear modulus, Young's modulus, Poisson's ratio, and Vickers hardness were 319 GPa, 182 GPa, 459 GPa, 0.26, and 24.0 GPa, respectively. The results revealed that Cr3C2 is more ductile than most covalent carbides, and its Vickers hardness is higher than that reported in previous studies. The intrinsic properties of Cr3C2 were obtained, which are relying on the advantages of sintering the pure polycrystalline ceramics.