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 ($5.8\times {10}^{-3}$ 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.

研究了钨（W）中空位和空位团簇的热演化。W（100）单晶用200 keV氢（H）离子辐照至低损伤水平（$5.8\times {10}^{-3}$dpa）在290 K下进行，然后在500–1800 K的温度范围内进行退火。由此产生的缺陷通过正电子lifetime没寿命谱（PALS）和正电子ni没多普勒展宽谱（DBS）进行表征。700 K退火导致形成包含10–15个空位的簇，而在800 K及更高温度下，形成包含大约20个或更多空位的簇。缺陷浓度的降低很可能伴随着簇的进一步粗化，从1300 K开始，直到1800 K结束，同时完全恢复了缺陷。在700 K和800 K下确定的簇尺寸大于在这些温度下热稳定的估计最小簇尺寸，这表明小簇的迁移和随后的聚结在簇生长中起重要作用。