Brittle and ductile behavior in carbon nanotubes

Large-scale molecular dynamics simulations were used to study the response of carbon nanotubes to a tensile load. Plastic or brittle behaviors can occur depending upon the external conditions and tube symmetry. All tubes rule: brittle at high strain and low temperature, while at low strain and high temperature: armchair (tl,rr) nanotubes can be completely or partially ductile. In zigzag (n,0) tubes ductile behavior is expected for tubes with n < 14, while larger tubes are completely brittle. In both cases the curvature determines the mechanical response. [S0031-9007(98)07696-0].