Bulk metallic glasses (BMGs) are a promising material group for applications in micro- and nano-electro-mechanical-systems due to their unique physical properties, such as a comparably high hardness and elastic limit paired with amorphous structure and certain glass specific traits.

Despite a lot of research, which is performed on BMGs, spare data is present for mechanical properties at the micrometer size regime, as required for the above usage. While all glasses suffer from shear localization, leading to macroscopic brittle behavior, inherently ductile glasses exist, which show extraordinary high resistance to crack propagation under bending load.

This special case of plasticity poses an issue to the conventional description of fracture toughness and therefore further detailed investigation on the fracture process is require. The present work strives for a deeper insight into the deformation mechanism and fracture behavior of a strong and ductile BMG, namely Pd77.5Cu6Si16.5, in the micrometer regime.

Multiple notched micro-mechanical samples in the shape of cantilevers were prepared by focused ion beam milling with different ligament sizes of 1, 2 and 5 µm, which were tested in-situ in a scanning electron microscope to observe the fracture process.

The specimens showed excessive blunting, which was captured with visual measurement of the crack tip opening displacement. Standardized fracture toughness models could not be applied due to a lack of significant crack propagation. Nevertheless, an significant size dependent behavior were documented.