Effect of pressure on anisotropy in elasticity, sound velocity, and thermal conductivity of vanadium borides

V2B3 is a potential superhard metal with low boride content that shows easily synthesized conditions and excellent mechanical properties and is used in armored equipment, aerospace, etc. fields by preparing laminated composite materials. However, the experimental study of the effect of pressure on the performance of V2B3 is complicated and laborious. Therefore, we use the first-principles method to analyze the mechanical properties and thermal conductivity of V(2)B(3 )under different pressures, hoping to provide a certain theoretical reference for the experiment. With the increased pressure, the hardness and ductility (ratio of bulk modulus (B) to shear modulus (G), B/G) increase simultaneously. The universal elastic anisotropic index (A(U)) and 3D surface contours of Young's modulus are used to describe the degree of elastic anisotropy. The strong anisotropy in elastic property is observed, and the anisotropic degree increases with the increased pressure. The values of sound velocities of pure transverse mode (v(t)) and slower mode (v(-)) are comparable and smaller than that of faster mode (v(+)). For these three-mode sound velocities, the anisotropies are relatively weak, and the variation trends of anisotropic degree under pressure show an obvious difference in different crystallographic planes. Under pressure, the minimum thermal conductivity increases and shows a pronounced anisotropy. Furthermore, the anisotropic degree increases with pressure.

Automated summary

In this study, the mechanical properties and thermal conductivity of V(2)B(3) under different pressures were analyzed using the first-principles method. The results show that with increased pressure, the hardness and ductility of V(2)B(3) increase. The elastic properties exhibit strong anisotropy, and the anisotropic degree increases with pressure. The thermal conductivity also shows pronounced anisotropy, with the minimum thermal conductivity increasing with pressure.