In-situ Zugversuche an einkristallinen Gold-Nanodrähten im TEM

The investigation of size dependent mechanical properties of different materials was of great interest for physicists over the past decades. Whereas the deformation of bulk materials is nearly completely understood and the underlying mechanisms are well known the situation for metals at the nano scale is different and still under discussion. Therefore, in this work the deformation of 40 – 250 nm thick, defect free, and single crystalline gold nanowires was investigated directly in the transmission electron microscope (TEM). These samples provide an ideal model system for such studies because one can eliminate the influence of the microstructure on deformation. In this work it was shown, that stacking faults appear during deformation as the result of the activation of partial dislocations. They nucleate homogenously along the wire length. Twins can be formed through the activation of partial dislocations on neighboring {111} planes. Both deformation mechanisms could be directly observed in TEM. An explanation for the findings is given with a model which describes the nucleation process of dislocations on the atomic scale. The model allows a quantitative estimation of the probability for each process to occur in the experiment and the corresponding stresses needed.