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Published December 4, 2014 | public
Journal Article

Microalloying Boron Carbide with Silicon to Achieve Dramatically Improved Ductility

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.

Additional Information

© 2014 American Chemical Society. Received: October 27, 2014; Accepted: November 18, 2014; Published: November 18, 2014. We thank Dr. Sergey Zybin and Dr. Andres Jaramillo-Botero at Caltech for the useful discussions. This work was supported by the Defense Advanced Research Projects Agency (W31P4Q-13-1-0010, program manager, Judah Goldwasser). The computers used in these studies were provided by NSF-CSEM and ONR-DURIP grants. The crystal structure was drawn using the VESTA software.

Additional details

Created:
August 20, 2023
Modified:
October 19, 2023