Fracture toughness characterization of single-crystalline tungsten using notched micro-cantilever specimens

• Fracture in tungsten on the small scale was investigated experimentally and numerically.
• The combined approach allows determining the fracture toughness despite the occurrence of plastic deformation.
• The micro fracture toughness value corresponds to the macroscopic one.
• Finally, a purely experimental procedure to determine the fracture toughness was proposed.

The fracture toughness of tungsten is strongly influenced by microstructural features including crystal orientation and grain structure as well as specimen or component size. In order to gain insight into the mechanical response of individual grains, an experimental study using small scale fracture specimens was conducted and closely accompanied by finite element simulations. Free-standing notched single-crystalline tungsten micro-bending beams with an orientation of the {011}〈01¯1〉-crack system along the loading direction were loaded using a nanoindenter and modelled using crystal plasticity and cohesive zones. This combined numerical and experimental approach successfully demonstrates a procedure to determine the fracture toughness of such small non-standard specimens despite the occurrence of plastic deformation.