A test device for in situ TEM investigations on failure behaviour of carbon nanotubes embedded in metals under tensile load

This paper presents an in situ pull-out test device to characterize interfaces between single-walled carbon nanotubes (SWCNTs) and metals. After summarizing results of maximum stresses calculated from molecular dynamics simulations and obtained from in situ scanning electron microscope experiments the need for an in situ experimental method with atomic resolution to study the mechanics of SWCNT-metal interfaces in further detail is outlined. For that purpose, a silicon-based micromechanical test stage with a thermal actuator for pull-out tests inside a transmission electron microscope was developed and characterized. To measure actuator movements digital image correlation was used. First experiments showed a stable movement of the metal electrode in the focal plane of the electron microscope. On the other hand, image drift due to the heat impact of the thermal actuators was observed. Finite element simulations were applied to further investigate the cause of the drift and to evaluate different approaches to solve the issue. Finally, a successful drift compensation by preheating the test device and keeping power consumption constant during the pull out experiment is demonstrated. In the future the presented system may be also used and further developed for in situ characterization of other materials.