Abstract
Reliable and accurate knowledge of the physical properties of elementary point defects is crucial for predictive modeling of the evolution of radiation damage in materials employed in harsh conditions. We have applied positron annihilation spectroscopy to directly detect mono-vacancy defects created in tungsten through particle irradiation at cryogenic temperatures, as well as their recovery kinetics. We find that efficient self-healing of the primary damage takes place through Frenkel pair recombination already at 35 K, in line with an upper bound of 0.1 eV for the migration barrier of self-interstitials. Further self-interstitial migration is observed above 50 K with activation energies in the range of 0.12–0.42 eV through the release of the self-interstitial atoms from impurities and structural defects and following recombination with mono-vacancies. Mono-vacancy migration is activated at around 550 K with a migration barrier of EmV=1.85±0.05 eV.
Highlights
A wide variety of methods has been employed to experimentally characterize early stage radiation damage recovery in tungsten, with the focus on self-interstitial atoms (SIAs) migration.11 More recently, Amino et al used high-voltage transmission electron microscopy to monitor low-temperature SIA dynamics.12,13 These studies are based on the detection of large defect clusters, such as dislocation loops or macroscopic properties, since the ability of the applied methods to detect point-like scitation.org/journal/apm defects is limited
We have applied positron annihilation spectroscopy to directly detect mono-vacancy defects created in tungsten through particle irradiation at cryogenic temperatures, as well as their recovery kinetics
We find that efficient self-healing of the primary damage takes place through Frenkel pair recombination already at 35 K, in line with an upper bound of 0.1 eV for the migration barrier of self-interstitials
Summary
A wide variety of methods has been employed to experimentally characterize early stage radiation damage recovery in tungsten, with the focus on SIA migration.11 More recently, Amino et al used high-voltage transmission electron microscopy to monitor low-temperature SIA dynamics.12,13 These studies are based on the detection of large defect clusters, such as dislocation loops or macroscopic properties, since the ability of the applied methods to detect point-like scitation.org/journal/apm defects is limited. We have applied positron annihilation spectroscopy to directly detect mono-vacancy defects created in tungsten through particle irradiation at cryogenic temperatures, as well as their recovery kinetics.
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