NSUF 20-2956: Atom Probe Studies on the ballistic mixing induced precipitates in heavy ion irradiated CuNb multilayers system
Multi-layered binary materials due to its huge volume of phase boundary and ultra-fine grain size are well investigated as conceptional materials for nuclear applications. The boundaries are considered as strong sink for interstitials and vacancies induced by irradiation. Accumulative roll bonding method has been successfully developed to produce industry size of CuNb multilayered compounds with average layer thickness as small as 18nm. However, one concern is under sever irradiation condition, the materials will lose their layer structures owing to ballistic mixing of displaced atoms. If these mixed atoms could diffuse back to its original layer, the layer structure will remain stable. Oppositely, the mixed atoms will stay in the intermediate layers, and form into precipitates when above a certain concentration. The hypothesis we proposed is the mixed atoms will be divided into three zones according to the distance from the layer boundary: 1) the denuded zone 2) precipitate zone and 3) isolated atoms zone. This divide is based on the balance with the ballistic mixing and back diffusion. Irradiations has been done in LANL already. The materials exhibited good resistance to irradiation as high as 100 dpa at 400 degree C. TEM work revealed that sphere shaped precipitates with diameter of 8~10nm were generated along the layer boundaries. Atom probe tomography offers a method to investigate the distribution profile of the atoms. If the distribution could be understood, we will be able to design the materials to avoid layer thickness within the precipitate distance to assure the layer structure to be preserved during heavy irradiation at required temperatures. Focused Ion Beam will be used to perform site specific sample preparation from irradiation region of the specimen followed by high resolution Atom Probe Tomography. The result will support the length scale in MD simulation work. The results will be published in peer-reviewed journals such as Journal of Nuclear Materials.
Additional Info
| Field | Value |
|---|---|
| Abstract | Multi-layered binary materials due to its huge volume of phase boundary and ultra-fine grain size are well investigated as conceptional materials for nuclear applications. The boundaries are considered as strong sink for interstitials and vacancies induced by irradiation. Accumulative roll bonding method has been successfully developed to produce industry size of CuNb multilayered compounds with average layer thickness as small as 18nm. However, one concern is under sever irradiation condition, the materials will lose their layer structures owing to ballistic mixing of displaced atoms. If these mixed atoms could diffuse back to its original layer, the layer structure will remain stable. Oppositely, the mixed atoms will stay in the intermediate layers, and form into precipitates when above a certain concentration. The hypothesis we proposed is the mixed atoms will be divided into three zones according to the distance from the layer boundary: 1) the denuded zone 2) precipitate zone and 3) isolated atoms zone. This divide is based on the balance with the ballistic mixing and back diffusion. Irradiations has been done in LANL already. The materials exhibited good resistance to irradiation as high as 100 dpa at 400 degree C. TEM work revealed that sphere shaped precipitates with diameter of 8~10nm were generated along the layer boundaries. Atom probe tomography offers a method to investigate the distribution profile of the atoms. If the distribution could be understood, we will be able to design the materials to avoid layer thickness within the precipitate distance to assure the layer structure to be preserved during heavy irradiation at required temperatures. Focused Ion Beam will be used to perform site specific sample preparation from irradiation region of the specimen followed by high resolution Atom Probe Tomography. The result will support the length scale in MD simulation work. The results will be published in peer-reviewed journals such as Journal of Nuclear Materials. |
| Award Announced Date | 2020-02-05T14:19:34.94 |
| Awarded Institution | None |
| Facility | None |
| Facility Tech Lead | Yaqiao Wu |
| Irradiation Facility | None |
| PI | Zhexian Zhang |
| PI Email | [email protected] |
| Project Type | RTE |
| RTE Number | 2956 |