Nanoprecipitates to Enhance Radiation Tolerance in High-Entropy Alloys

Area of Science:

• Materials Science
• Nuclear Engineering
• Physical Metallurgy

Background:

• Advanced energy technologies require structural materials capable of withstanding extreme environments like high temperatures and radiation.
• High-entropy alloys (HEAs) are promising but can suffer from void swelling at high radiation doses (>50 dpa), limiting their use in nuclear reactors.
• Current HEAs often exhibit limited radiation tolerance, necessitating the development of improved materials for demanding applications.

Purpose of the Study:

• To develop a novel high-entropy alloy with enhanced resistance to radiation damage.
• To investigate the effect of Cu-rich nanoprecipitates on the radiation tolerance of HEAs.
• To understand the underlying mechanisms responsible for improved radiation resistance in engineered HEAs.

Main Methods:

• Development of a novel HEA composition: NiCoFeCrCu_0.12, incorporating a high density of Cu-rich nanoprecipitates.
• High-dose irradiation experiments to assess void swelling and hardening up to >100 dpa.
• Density functional theory (DFT) simulations to investigate defect formation energies and interface behavior.

Main Results:

• The NiCoFeCrCu_0.12 HEA demonstrated excellent void swelling resistance and negligible radiation-induced hardening at doses exceeding 100 dpa.
• Void swelling resistance was significantly superior compared to NiCoFeCr concentrated solid solution alloys (CSAs) and austenitic stainless steels.
• DFT simulations predicted lower vacancy and interstitial formation energies at coherent nanoprecipitate-matrix interfaces, facilitating effective recombination.

Conclusions:

• The incorporation of Cu-rich nanoprecipitates and their coherent interfaces is a critical mechanism for achieving high radiation tolerance in HEAs.
• This materials design strategy, utilizing a high density of interfaces, effectively mitigates radiation damage by promoting vacancy-interstitial recombination.
• The developed HEA offers a promising solution for structural materials in advanced nuclear reactors and other high-radiation environments.