Atomistic Explanation of Shear-Induced Amorphous Band Formation in Boron Carbide

Qi An, William A. Goddard, III, and Tao Cheng
Phys. Rev. Lett. 113, 095501 – Published 28 August 2014
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Abstract

Boron carbide (B4C) is very hard, but its applications are hindered by stress-induced amorphous band formation. To explain this behavior, we used density function theory (Perdew-Burke-Ernzerhof flavor) to examine the response to shear along 11 plausible slip systems. We found that the (011¯1¯)/1¯101 slip system has the lowest shear strength (consistent with previous experimental studies) and that this slip leads to a unique plastic deformation before failure in which a boron-carbon bond between neighboring icosahedral clusters breaks to form a carbon lone pair (Lewis base) on the C within the icosahedron. Further shear then leads this Lewis base C to form a new bond with the Lewis acidic B in the middle of a CBC chain. This then initiates destruction of this icosahedron. The result is the amorphous structure observed experimentally. We suggest how this insight could be used to strengthen B4C.

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  • Received 12 May 2014

DOI:https://doi.org/10.1103/PhysRevLett.113.095501

© 2014 American Physical Society

Authors & Affiliations

Qi An, William A. Goddard, III*, and Tao Cheng

  • Materials and Process Simulation Center, California Institute of Technology, Pasadena, California 91125, USA

  • *Corresponding author. wag@wag.caltech.edu

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Issue

Vol. 113, Iss. 9 — 29 August 2014

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