Strengthening boron carbide by doping Si into grain boundaries

YD Shen and MY Yang and WA Goddard and Q An, JOURNAL OF THE AMERICAN CERAMIC SOCIETY (2021).

DOI: 10.1111/jace.18028

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.

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