Microalloying Boron Carbide with Silicon to Achieve Dramatically Improved Ductility
Qi An, William A. Goddard III
Abstract
Boron carbide (B_4C) is a hard material whose value for extended engineering applications such as body armor; is limited by its brittleness under impact. To improve the ductility while retaining hardness, we used density functional theory to examine modifying B_4C ductility through microalloying. We found that replacing the CBC chain in B_4C with Si–Si, denoted as (B_(11)C_p)–S_i_2, dramatically improves the ductility, allowing a continuous shear to a large strain of 0.802 (about twice of B_4C failure strain) without brittle failure. Moreover, (B_(11)C)–Si_2 retains low density and high hardness. This ductility improvement arises because the Si–Si linkages enable the icosahedra accommodate additional shear by rotating instead of breaking bonds.
Group Members
An, Q. & III, W. A. G. (2014). Microalloying Boron Carbide with Silicon to Achieve Dramatically Improved Ductility. *J. Phys. Chem. Lett.*, *5*(23), 4169-4174. https://doi.org/10.1021/jz5022697