Ultra-high purity (> 99.9999 wt%) chemical vapour deposited tungsten (CVD–W) samples were neutron irradiated in the BR2 reactor (Belgium) at Tirr < 210 °C to ~ 0.15 dpa, followed by isochronal annealing at 500, 800 and 1100 °C. Defect characterization showed that dislocation loops dominated the as-irradiated damage microstructure and were mostly ≤5 nm. Void formation was observed after post-irradiation annealing at 1100 °C. The mechanical and thermal properties of CVD-W were evaluated based on tensile tests, Vickers hardness and temperature wave analysis. Fractography study suggested that a transition from intergranular fracture to cleavage fracture took place in the material after neutron irradiation. Hardening was found ~ 23% after irradiation. Subsequent annealing below 800 °C saw further increase in hardness, featuring a maximum value of about Hv = 487. Softening occurred at 1100 °C. Thermal diffusivity dropped by ~ 65% after irradiation and ~ 40% of this degradation recovered at 1100 °C.
|Journal||International Journal of Refractory Metals and Hard Materials|
|Publication status||Published - 2019 Dec|
- Mechanical properties
- Neutron irradiation
- Thermal properties