In Situ TEM tensile testing of bicrystals with tailored misorientation angles

Grain boundaries have complex structural features that influence strength, ductility and fracture in met -als and alloys. Grain boundary misorientation angle has been identified as a key parameter that controls their mechanical behavior, but the effect of misorientation angle has been challenging to isolate in poly-crystalline materials. Here, we describe the use of bicrystal Au thin films made using a rapid melt growth process to study deformation at a single grain boundary. Tensile testing is performed on bicrystals with different misorientation angles using in situ TEM, as well as on a single crystalline sample. Plastic de-formation is initiated through dislocation nucleation from free surfaces. Grain boundary sliding is not observed, and failure occurs away from the grain boundary through plastic collapse in all cases. The fail-ure behavior in these nanoscale bicrystals does not appear to depend on the misorientation angle or grain boundary energy but instead has a more complex dependence on sample surface structure and dislocation activity.(c) 2021 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Automated summary

Grain boundaries in metals and alloys have complex structural features that affect their mechanical behavior. This study used bicrystal Au thin films to investigate deformation at a single grain boundary and found that the misorientation angle of the grain boundary has minimal influence.