Characterization of Powder Injection Molded and Spark Plasma Sintered Tungsten Materials as Plasma Facing Materials for DEMO

Tungsten based materials are attractive to be used in various applications for fusion power plants. Besides its advantages the main drawbacks are its brittleness and correlated difficult machinability as well as the narrow range of possible alloys using the commercial fabrication route. Both issues are addressed by the development and fabrication of complex near-net shaped tungsten parts via Powder Injection Molding (PIM). R&D in this field is done within the EUROfusion materials development project, where various PIM-W materials were investigated and W-1TiC and W2Y2O3 were yet selected as the most promising material compositions which will also be subject to neutron irradiation studies in the future.
Outside of the EUROfusion project, alternative material development is ongoing using different approaches concerning manufacturing method and variations in composition. One of these methods is spark plasma sintering (SPS) and the material compositions produced are W-2.5TiC, W-0.3Ti-2Ta-0.5Y and W-10Cr-1Hf.
Characterization of the materials was performed determining the materials microstructure and hardness and by performing high heat flux testing in the electron beam facility JUDITH-1. ... mehrThereby, 100 and 1000 ELM-like thermal shock loads were applied at base temperatures of 400 °C and 1000 °C and with power densities of up to 0.38 GW/m2. These conditions are in the range of the damage threshold for commercial reference tungsten grades, thus allowing the qualification of the individual materials towards this reference material and amongst each other.
The qualification and quantification of the materials performance and damage was done by relating the material microstructural and mechanical properties with the results obtained by post-mortem examinations using profilometry and metallographic means. The focus thereby is put on the thermal shock induced thermal fatigue damage comprised of surface roughening and crack formation, being a direct measure of the thermal fatigue resistance of the material. In addition, due to the short manufacturing time using SPS, thermal annealing at different temperatures for 1h was performed in order to determine the thermal stability of the material’s microstructure.