B11-O-10In situ Atomic Scale Mechanical Microscopy

Abstract

We developed in situ atomic scale mechanical microscopy (ASM) for investigation of the deformation dynamics of materials with simultaneous atomic scale imaging. The In situ TEM mechanical testing techniques are generally applicable to regular TEM samples by tensile experiment with simultaneous double tilt, and thus the ability of obtaining atomic scale imaging about the deformation dynamics of the deformed materials. We show several examples of the atomic scale deformation dynamics of Ni, Pt, Au and Cu as well as Cu-Zr metallic glass. It was revealed that these materials show unusual large strain elasticity, size-dependent elasto-plastic transitions and the unusual plasticity behaviors at nano-scale. For example, the cross-over plasticity mechanisms from partial dislocation to full dislocation and twins were discovered in deformation of nano single crystalline Cu samples. A long standing puzzle and uncertainties of grain rotation in ultra-small nano-sized polycrystalline materials (grain size less than 8nm) was demonstrated through this in situ: ASM. It was uncovered that the dislocation climb takes care of the grain rotation behaviors in small grain systems. These results shed lights in understanding the interesting mechanical behaviors and the related dislocation activities of the metallic materials at small scale and useful for designing new materials with strength and ductility as well as those applications in micro- and nano- electronics and mechanics.