Abstract
The thermal evolution of vacancies and vacancy clusters in tungsten (W) has been studied. W (100) single crystals were irradiated with 200 keV hydrogen (H) ions to a low damage level (5.8×10−3 dpa) at 290 K and then annealed at temperatures in the range of 500–1800 K. The resulting defects were characterized by positron annihilation lifetime spectroscopy (PALS) and positron annihilation Doppler broadening spectroscopy (DBS). Annealing at 700 K resulted in the formation of clusters containing 10–15 vacancies, while at 800 K and higher temperatures clusters containing about 20 vacancies or more were formed. Reduction of the defect concentration likely accompanied by further coarsening of the clusters started at 1300 K and ended at 1800 K with the complete defect recovery. The determined cluster sizes at 700 K and 800 K were larger than the estimated minimum cluster sizes that are thermally stable at these temperatures, indicating that the migration and ensuing coalescence of small clusters plays an important role in cluster growth.
| Original language | English |
|---|---|
| Article number | 152017 |
| Journal | Journal of Nuclear Materials |
| Volume | 531 |
| DOIs | |
| Publication status | Published - Apr 2020 |
| MoE publication type | A1 Journal article-refereed |
Funding
J.H. and F.T. acknowledge the financial support from the Academy of Finland project Nr. 315082 . This work was supported by the European Commission and carried out within the framework of the Erasmus Mundus International Doctoral College in Fusion Science and Engineering (FUSION-DC). This work has also been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014–2018 and 2019–2020 under grant agreement No 633053.
Keywords
- Positron annihilation
- Radiation defects
- Tungsten
- Vacancies
- Vacancy clusters