Critical Shear Stress of Rhodium Nanocontacts Studied by In Situ High-Resolution Transmission Electron Microscopy

The structural dynamics during tensile deformation of rhodium (Rh) nanocontacts (NCs) at room temperature was observed by in situ high-resolution transmission electron microscopy. The critical shear stress for a {111}-< 110 > slip system was estimated from simultaneous measurement of the force acting on the NCs. It was found that the critical shear stress increased to similar to 5 GPa, which was comparable with that for a homogeneous slip, as the minimum cross-sectional width of the NCs decreased to less than 1.6 nm. This result implies that the slip mechanism in Rh transformed from dislocation-mediated slip to homogeneous slip when the width decreased to less than the critical size.