Real-time fracture detection of individual boron nitride nanotubes in severe cyclic deformation processes

Real-time deformation of individual multiwalled boron nitride nanotubes (BNNTs) was investigated using an atomic force microscopy (AFM) stage installed inside the chamber of a transmission electron microscopy (TEM) system. These in situ AFM-TEM experiments were conducted in following two deformation regimes: a small-angle (similar to 65 degrees) and a large-angle (similar to 120 degrees) cyclic bending process. BNNTs survived from the low-angle test and their modulus was determined as similar to 0.5 TPa. Fracture failure of individual BNNTs was discovered in the large-angle cyclic bending. The brittle failure mechanism was initiated from the outermost walls and propagated toward the tubular axis with discrete drops of applied forces. (C) 2010 American Institute of Physics. [doi:10.1063/1.3456083]