Tungsten alloys are candidate materials for future fusion reactors. Their high melting points, high thermal conductivity and high erosion resistances are crucial in these environments. Since tungsten is a bcc metal, its fracture behaviour changes from ductile at high temperatures to brittle at low temperatures. The fracture behaviour of pure tungsten and two tungsten alloys (WL10 and WVM) was therefore studied, taking into account the influence of temperature (77K-800°C) and fabrication condition. High Pressure Torsion (HPT) is a simple method of Severe Plastic Deformation to produce bulk nanostructured materials, which offer extraordinary material properties. This technique was therefore applied to three tungsten alloys (pure W, WL10 and WVM) to explore a possible improvement of fracture toughness. The influence of HPT on properties is profound, the structural size is decreased to 300 nm, whereas hardness and fracture toughness at room temperature are increased to 3000MPa and 30 MPam^0.5, respectively. Possible reasons for the remarkable change in mechanical properties are discussed.