NSUF 23-4720: Recovery of Irradiated Tantalum, a Pre-Cursor to Understanding Ferritic (BCC) Steels
We plan to establish a microstructural analogy of “separate effects testing” to understand the unique roles that distinct microstructural features play in determining the evolution of properties under fission prototypic environments. In hierarchical order of complexity, beginning with simple elemental Ta, we will understand how dislocations develop and affect the strength and ductility of the material. Moving to a more complicated BCC ferritic steel we will establish the additional strengthening effect of the irradiation induced minor phases. This work fits in with our currently funded effort (funding agency) to develop micro-aware models of deformation and recovery of BCC steels and LANL internal (LDRD) funding to understand Refractory High Entropy Alloys. Ferritic (BCC) steels have been presented as one of the leading candidates for structural materials in fast, fusion, and Gen IV reactors due to their superior resistance to radiation-induced swelling and creep and reasonable high temperature strength as compared with austenitic steels. However, ferritic steels have complex microstructures, especially after irradiation, which makes detailed modeling of the deformation and recovery process very difficult. Pure tantalum is proposed as a single element, body centered cubic analog material that removes many of the complicating factors associated with alloy steels, e.g. minor phases, solute chemistry, etc. Coupled experimentation and modeling of irradiated tantalum, will allow us to answer the simpler problem first, and validate model forms used in the more complex microstructure of ferritic steels. This proposal seeks to obtain several irradiated tantalum samples from the Nuclear Fuels and Materials Library with ID Codes ~ 111-EBR (Tensile Sample) and 137-EBR (Hardness Sample). These samples will be used in a multi-year campaign of experiments at the Los Alamos Neutron Scattering Center (LANSCE). Initially, the crystallographic textures, dislocation density and coherent crystallite size will be determined through established measurement and analysis techniques on the HIPPO and SMARTS diffractometers, respectively. Subsequently, in-situ tensile and compressive neutron diffraction experiments will be performed on the irradiated material deformed to different strain levels within the SMARTS diffractometer at the Lujan Center at LANSCE. These experiments will enable in-situ monitoring of the evolution of the microstructure, specifically the dislocation density and texture. Finally, the recovery of the dislocations which have been imparted both by irradiation as well as irradiation followed by deformation will be monitored though in-situ diffraction measurements at elevated temperature (annealing). This series of measurements closely parallels recent measurements (not yet published) on non-irradiated tantalum completed as part of distinct programs at LANL. The data collected will be used to develop microstructure-aware models of the deformation and recovery of the simplest possible material system with an eye specifically towards how the defects introduced by irradiation alter the relationship between the microstructure and observed strength of the materials.
Additional Info
| Field | Value |
|---|---|
| Abstract | We plan to establish a microstructural analogy of “separate effects testing” to understand the unique roles that distinct microstructural features play in determining the evolution of properties under fission prototypic environments. In hierarchical order of complexity, beginning with simple elemental Ta, we will understand how dislocations develop and affect the strength and ductility of the material. Moving to a more complicated BCC ferritic steel we will establish the additional strengthening effect of the irradiation induced minor phases. This work fits in with our currently funded effort (funding agency) to develop micro-aware models of deformation and recovery of BCC steels and LANL internal (LDRD) funding to understand Refractory High Entropy Alloys. Ferritic (BCC) steels have been presented as one of the leading candidates for structural materials in fast, fusion, and Gen IV reactors due to their superior resistance to radiation-induced swelling and creep and reasonable high temperature strength as compared with austenitic steels. However, ferritic steels have complex microstructures, especially after irradiation, which makes detailed modeling of the deformation and recovery process very difficult. Pure tantalum is proposed as a single element, body centered cubic analog material that removes many of the complicating factors associated with alloy steels, e.g. minor phases, solute chemistry, etc. Coupled experimentation and modeling of irradiated tantalum, will allow us to answer the simpler problem first, and validate model forms used in the more complex microstructure of ferritic steels. This proposal seeks to obtain several irradiated tantalum samples from the Nuclear Fuels and Materials Library with ID Codes ~ 111-EBR (Tensile Sample) and 137-EBR (Hardness Sample). These samples will be used in a multi-year campaign of experiments at the Los Alamos Neutron Scattering Center (LANSCE). Initially, the crystallographic textures, dislocation density and coherent crystallite size will be determined through established measurement and analysis techniques on the HIPPO and SMARTS diffractometers, respectively. Subsequently, in-situ tensile and compressive neutron diffraction experiments will be performed on the irradiated material deformed to different strain levels within the SMARTS diffractometer at the Lujan Center at LANSCE. These experiments will enable in-situ monitoring of the evolution of the microstructure, specifically the dislocation density and texture. Finally, the recovery of the dislocations which have been imparted both by irradiation as well as irradiation followed by deformation will be monitored though in-situ diffraction measurements at elevated temperature (annealing). This series of measurements closely parallels recent measurements (not yet published) on non-irradiated tantalum completed as part of distinct programs at LANL. The data collected will be used to develop microstructure-aware models of the deformation and recovery of the simplest possible material system with an eye specifically towards how the defects introduced by irradiation alter the relationship between the microstructure and observed strength of the materials. |
| Award Announced Date | 2023-06-01T09:08:00.603 |
| Awarded Institution | None |
| Facility | None |
| Facility Tech Lead | Alina Zackrone, Tarik Saleh |
| Irradiation Facility | None |
| PI | Aaron Kohnert |
| PI Email | [email protected] |
| Project Type | RTE |
| RTE Number | None |