Microalloying Boron Carbide with Silicon to Achieve Dramatically Improved Ductility

Abstract

Boron carbide (B4C) 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 B4C ductility through microalloying. We found that replacing the CBC chain in B4C with Si Si, denoted as (B11Cp) Si2, dramatically improves the ductility, allowing a continuous shear to a large strain of 0.802 (about twice of B4C failure strain) without brittle failure. Moreover, (B11C) Si2 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.

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Document Details

Document Type
Technical Report
Publication Date
Nov 18, 2014
Accession Number
ADA618305

Entities

People

  • Qi An
  • William Andrew Goddard III

Organizations

  • California Institute of Technology

Tags

Communities of Interest

  • Air Platforms

DTIC Thesaurus Topics

  • Atoms
  • Boron Carbides
  • Bulk Modulus
  • Chemistry
  • Crystal Structure
  • Density Functional Theory
  • Engineering
  • Ground State
  • Low Density
  • Mechanical Properties
  • Mechanics
  • Optical Materials
  • Physical Chemistry
  • Shear Modulus
  • Shear Strength
  • Stresses
  • Wear Resistance

Readers

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