Strengthening boron carbide by doping Si into grain boundaries

Abstract

Grain boundaries, ubiquitous in real materials, play an important role in the mechanical properties of ceramics. Using boron carbide as a typical superhard but brittle material under hypervelocity impact, we report atomistic reactive molecular dynamics simulations using the ReaxFF reactive force field fitted to quantum mechanics to examine grain boundary engineering strategies aimed at improving the mechanical properties. In particular, we examine the dynamical mechanical response of two grain boundary models with or without doped Si as a function of finite shear deformation. Our simulations show that doping Si into the grain boundary significantly increases the shear strength and stress threshold for amorphization and failure for both grain boundary structures.These results provide validation of our suggestions that Si doping provides a promising approach to mitigate amorphous band formation and failure in superhard boron carbide.

Microstructure and mechanical properties of WB2–B4C composites fabricated by boro/carbothermal reduction and SPS

“…This could be attributed to the fact that when the applied load exceeds its Hugoniot elastic limit during the indenter loading, the B-C bond and icosahedral structure of B 4 C could be destroyed accompanied with the formation of amorphous structure. 58,59 The amorphization of B 4 C might prevent it from broad engineering applications, 60,61 which would require further in-depth study.…”