Superstrength through Nanotwinning

• DOI: 10.1021/acs.nanolett.6b03414
• Publication Date: 2016-11-07T19:09:18Z
• Authors: Qi An; William A. Goddard; Kelvin Y. Xie; Gi-dong Sim; Kevin J. Hemker; Tyler Munhollon; M. Fatih Toksoy; Richard A. Haber
• Keywords: Boron carbide; Perfect crystal; Indentation; Crystal (programming language)

The theoretical strength of a material is the minimum stress to deform or fracture perfect single crystal that has no defects. This considered as an upper bound on attainable for real crystal. In contradiction this expectation, we use quantum mechanics (QM) simulations show boron carbide (B4C) hard ceramic, shear can be exceeded by 11% imposing nanoscale twins. We also predict from QM indentation nanotwinned B4C 12% higher than Further, validate effect experimentally, showing samples are harder 2.3% twin-free counterpart B4C. origin strengthening mechanism suppression twin boundary (TB) slip within nanotwins due directional nature covalent bonds at TB.