Strain-and temperature-induced dilatancy in ZrNi thin film metallic glasses with nanoscale structural heterogeneities
摘要
Thin film metallic glasses (TFMG) provide rich information on plastic phenomena owing to a more ductile behaviour than bulk counterparts. However, correlation between the macroscopic and the atomic strain for sub-micron scale specimens remains a challenge which is essential towards unravelling the origin of the mechanical properties. Here, complementary results were obtained combining high-resolution X-ray synchrotron scattering and in situ annealing transmission electron microscopy measurements on ZrNi thin freestanding films showing remarkable strength/ductility balance. The evolution of the structure factor shows the occurrence of spatially homogeneous and isotropic atomic dilatancy without shear banding upon tensile loading at room temperature. The in situ TEM results reveal that such dilatancy is also triggered during thermal annealing but only in undeformed samples. The discussion aims at linking this behaviour to the specific microstructure of the films, which involves nanoscale chemical/density heterogeneities inherited from the deposition process, and to the mechanical properties.
Graphical Abstract