Tungsten and tungsten-based materials show a very strong relationship between processing history, microstructure and mechanical properties. W-based refractory metals show excellent properties at elevated temperatures such as high strength, good thermal conductivity and low sputtering yield. However, brittle fracture behaviour with low fracture toughness values, in some cases even at elevated temperatures, can be major drawbacks for their use in structural applications. Aside from a basic understanding of the micro- and nano-scale mechanisms determining deformation mechanisms on the macro-scale, scientific research efforts in the past decade were mainly driven by the application of tungsten-based materials in future fusion reactors.
In this presentation we will review various approaches for improving the mechanical performance of tungsten material, such as alloying, improved processing routes, including severe plastic deformation, and composite production, to name a few. From a methodological point of view, experimental work on various length scales as well as density functional theory calculations are encompassed. Experiments, mainly focussing on fracture experiments, deal with different starting microstructures: rolled plates and foils, swaged rods, drawn wires and severely deformed nanocrystalline structures. Density functional theory calculations, dealing with the movement of dislocations and segregation of elements unveil consequences for processes observed at much longer length scales.