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Atomic-Scale Hidden Point-Defect Complexes Induce Ultrahigh-Irradiation Hardening in Tungsten
Ruo-Yao Zheng1, Wu-Rong Jian2, Irene J Beyerlein2,3
1Center for Advancing Materials Performance from the Nanoscale, State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an 710049, China.
Nano Letters
|July 6, 2021
Summary
Tungsten
Area of Science:
- Materials Science
- Nuclear Engineering
- Physics
Background:
- Tungsten is a key material for fusion reactors due to its high-temperature strength.
- Irradiation hardening in tungsten limits its service life and raises safety concerns.
- Conventional theories do not fully explain tungsten's extreme hardening under irradiation.
Purpose of the Study:
- To investigate the origin of ultrahigh-irradiation hardening in tungsten.
- To identify the primary mechanisms responsible for strength increases in irradiated tungsten.
Main Methods:
- In situ nanomechanical testing of irradiated tungsten.
- Atomistic simulations and calculations.
- Analysis of helium ion irradiation and defect distribution.
Main Results:
- Tungsten's strength increased nearly threefold after irradiation.
- Conventional defects account for less than one-third of the observed hardening.
- A significant fraction of vacancies and helium atoms were unaccounted for.
- High densities of atomic-scale hidden point-defect complexes were identified as the main hardening source.
Conclusions:
- Irradiation hardening in tungsten is primarily caused by atomic-scale hidden point-defect complexes.
- This finding challenges conventional strengthening theories for irradiated metals.
- Understanding these complexes is crucial for predicting tungsten's performance in fusion environments.
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