Fracture strength and microstructure of ODS tungsten alloys

Abstract In many high temperature applications tungsten is superior to molybdenum alloys. For structural components very often joining technology is the limiting factor. If brazing or welding is used ductility at room temperature has to be considered. Particularly when handling or transporting they run the risk of brittle fracture. Relevant properties are sufficient fracture strength and ductility at ambient temperatures after high temperature annealing as well as high recrystallization temperature. We studied several tungsten alloys performing 3 point bending tests, annealing experiments and metallographic examinations. In respect to environmental considerations possible alloys should not contain thoria. Alloying with rare earth oxides enhance the fracture strength at ambient temperatures after high temperature annealing and increases the recrystallization start temperature. The results indicate that suitable thermomechanical treatment increases the recrystallization temperature by more than 500 °C and improve the fracture strength by a factor of 1.5. Favourable results with Th-free tungsten alloys are possible.