Fracture behaviour of tungsten-vanadium and tungsten-tantalum alloys and composites

The influence of both microstructure and chemical composition on the fracture behaviour of tungsten-tantalum, tungsten-vanadium composites and alloys of varying chemical compositions are investigated. Industrial solid solution tungsten-tantalum alloys with different tantalum contents in the as-forged condition are investigated along with different tungsten-tantalum and tungsten-vanadium composites and alloys made by powder consolidation, severe plastic deformation using high pressure torsion and different subsequent heat treatments. To investigate the fracture behaviour, several crack propagation directions in relation to the forging direction and shear direction, respectively, are taken into account. Heat treatment of the composite material results in a more homogeneous distribution of the alloying element and the impacts of these specific heat treatments on microstructure and fracture toughness are discussed. The fracture experiments are performed within a temperature range from room temperature to 600 °C and reveal a strong dependence of the fracture toughness and fracture morphology on temperature and on the microstructure, and hence the processing history of the materials.