Experimental investigation of the fracture toughness of polycrystalline tungsten in the brittle and semi-brittle regime

Tungsten is of special interest for the application as a plasma facing material in future fusion reactors. One drawback of tungsten as a structural material is that the brittle-to-ductile transition occurs at relatively high temperatures and thus tungsten is inherent brittle. In this work the fracture behavior and the fracture toughness of notched specimens are determined as a function of temperature in the brittle and semi-brittle regime. The influence of the microstructure of rolled polycrystalline tungsten on the fracture process is studied for different crack orientations relative to its texture. To gain insight in the responsible failure mechanisms the crack paths and the morphology of the fracture surfaces are characterized by means of scanning electron microscopy.