NSUF 23-4694: Mechanisms of Outstanding Radiation Tolerance in High Entropy Alloys with Nanoprecipitates
The growth of advanced energy technologies for power generation is enabled by the design, development, and integration of structural materials that can withstand extreme environments, such as high temperatures, radiation damage, and corrosion. High-entropy alloys (HEAs) are a class of structural materials in which suitable chemical elements in four or more numbers are mixed to typically produce single-phase concentrated solid solution alloys (CSAs). Many of these alloys exhibit good radiation tolerance, like limited void swelling and hardening upto relatively medium radiation doses (tens of displacements per atom (dpa)); however, at higher radiation damage levels (>50 dpa), some HEAs suffer from considerable void swelling limiting their near-term acceptance for advanced nuclear reactor concepts. In our work, we developed a HEA containing a high density of Cu-rich nanoprecipitates distributed in the HEA matrix. The Cu-added HEA, NiCoFeCrCu0.12, shows excellent void swelling resistance and negligible radiation-induced hardening upon irradiation up to high radiation doses (i.e., higher than 100 dpa). The void swelling resistance of the alloy is measured to be significantly better than NiCoFeCr CSA and austenitic stainless steels.
We hypothesize that the effective point defects recombination at the nanoprecipitates’ coherent interface enables the high radiation resistance in NiCoFeCrCu0.12 HEA. The density functional theory calculations estimated lower point defect formation energies at the interfaces supporting our claim. Since all our analyses are based upon ex-situ irradiations and observations, the experimental observation of the basic mechanisms responsible for the radiation tolerance of NiCoFeCrCu0.12 is lacking. Thus, we propose to use in-situ transmission electron microscopy (TEM) irradiation techniques to see the radiation-induced evolution of defects and chemistry in the Cu-added HEA. The in-situ TEM irradiation experiments will investigate the evolution of extended defects, such as dislocations and voids, the utility of Cu nanoprecipitates’ interfaces in NiCoFeCrCu0.12 HEA for defect formation and growth, and the phase stability of the nanoprecipitates under irradiation. Furthermore, we will also irradiate 14YWT oxide dispersion strengthened (ODS) steel under similar conditions to compare the radiation behavior with HEAs. To this end, we will use a focused ion beam system and 300 kV FEI Technai TEM available at the Michigan Ion Beam Laboratory (MIBL). The proposed work will be completed in six months from the time of the award.
The scientific outcomes of the proposed work will expand the current state of the knowledge on understanding the influence of chemical complexity and second phases in HEA systems. Such multiphase HEA systems have been showing promising properties in terms of radiation tolerance and mechanical performance for applications in extreme environments, such as advanced reactor concepts. We will disseminate the scientific outcomes through a high-impact journal publication.
Additional Info
| Field | Value |
|---|---|
| Abstract | The growth of advanced energy technologies for power generation is enabled by the design, development, and integration of structural materials that can withstand extreme environments, such as high temperatures, radiation damage, and corrosion. High-entropy alloys (HEAs) are a class of structural materials in which suitable chemical elements in four or more numbers are mixed to typically produce single-phase concentrated solid solution alloys (CSAs). Many of these alloys exhibit good radiation tolerance, like limited void swelling and hardening upto relatively medium radiation doses (tens of displacements per atom (dpa)); however, at higher radiation damage levels (>50 dpa), some HEAs suffer from considerable void swelling limiting their near-term acceptance for advanced nuclear reactor concepts. In our work, we developed a HEA containing a high density of Cu-rich nanoprecipitates distributed in the HEA matrix. The Cu-added HEA, NiCoFeCrCu0.12, shows excellent void swelling resistance and negligible radiation-induced hardening upon irradiation up to high radiation doses (i.e., higher than 100 dpa). The void swelling resistance of the alloy is measured to be significantly better than NiCoFeCr CSA and austenitic stainless steels. We hypothesize that the effective point defects recombination at the nanoprecipitates’ coherent interface enables the high radiation resistance in NiCoFeCrCu0.12 HEA. The density functional theory calculations estimated lower point defect formation energies at the interfaces supporting our claim. Since all our analyses are based upon ex-situ irradiations and observations, the experimental observation of the basic mechanisms responsible for the radiation tolerance of NiCoFeCrCu0.12 is lacking. Thus, we propose to use in-situ transmission electron microscopy (TEM) irradiation techniques to see the radiation-induced evolution of defects and chemistry in the Cu-added HEA. The in-situ TEM irradiation experiments will investigate the evolution of extended defects, such as dislocations and voids, the utility of Cu nanoprecipitates’ interfaces in NiCoFeCrCu0.12 HEA for defect formation and growth, and the phase stability of the nanoprecipitates under irradiation. Furthermore, we will also irradiate 14YWT oxide dispersion strengthened (ODS) steel under similar conditions to compare the radiation behavior with HEAs. To this end, we will use a focused ion beam system and 300 kV FEI Technai TEM available at the Michigan Ion Beam Laboratory (MIBL). The proposed work will be completed in six months from the time of the award. The scientific outcomes of the proposed work will expand the current state of the knowledge on understanding the influence of chemical complexity and second phases in HEA systems. Such multiphase HEA systems have been showing promising properties in terms of radiation tolerance and mechanical performance for applications in extreme environments, such as advanced reactor concepts. We will disseminate the scientific outcomes through a high-impact journal publication. |
| Award Announced Date | 2023-06-01T09:00:52.857 |
| Awarded Institution | None |
| Facility | None |
| Facility Tech Lead | Kevin Field |
| Irradiation Facility | None |
| PI | Boopathy Kombaiah |
| PI Email | [email protected] |
| Project Type | RTE |
| RTE Number | None |