In situ atomistic observation of the deformation mechanism of Au nanowires with twin-twin intersection

Twin-twin intersections are often observed in face-centered cubic (FCC) metallic nanostructures, which have important contributions to the plastic deformation and strengthening of FCC metals with low stacking fault energies. However, a deep insight into the underlying mechanism involved in the formation and evolution of twin-twin intersections remains largely lacking, especially in experiments. Here, by conducting the in situ straining experiments under high resolution transmission electron microscope (TEM), we directly visualize the dynamic evolution of a twin-twin intersection in Au nanowire at the nanoscale. It shows that dislocations in the incoming twin can either glide onto or transmit across the barrier twin via dislocation interaction with the twin boundary, resulting in the twin-twin intersection. Dynamic twinning and de-twinning of the twin-twin intersection govern the whole deformation of the nanowire. These findings reveal the dynamic behaviors of twin-twin intersection under mechanical loading, which benefits further exploration of FCC metals and engineering alloys with twin-twin intersection structures. (C) 2020 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.