Details

Autor(en) / Beteiligte

• An, Qi
• Goddard, 3rd, William A
• Cheng, Tao

Titel

Atomistic explanation of shear-induced amorphous band formation in boron carbide

Ist Teil von

• Physical review letters, 2014-08, Vol.113 (9), p.095501-095501, Article 095501

Ort / Verlag

United States

Erscheinungsjahr

2014

Quelle

PROLA - Physical Review Online Archive

Beschreibungen/Notizen

• 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 (0111)/ 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.