NSUF 18-1469: Investigation of neutron irradiation effects on Zr based bulk metallic glass (BMG) via advanced in situ mechanical testing and microstructural analysis.
Recently, Zr based BMGs have been reported to have properties that are superior to that of conventional alloys, such as high strength and hardness, wear resistance, and corrosion resistance, which make it potentially suited for extreme environments. In addition, bulk metallic glasses are thought to have high helium permeability, due to their large free atomic volume and lack of grain boundaries which can act as helium traps. As such, this class of materials have been proposed as potential materials for nuclear applications. However, not much is known about the effects of neutron irradiation on the microstructure and mechanical properties of amorphous alloys. Therefore, the purpose of this investigation is to gain a more fundamental scientific understanding of the effects of irradiation displacement damage in a Zr based bulk metallic glass. It will be hypothesized here that neutron irradiation leads to structural rejuvenation in the BAM-11. Furthermore, it is believed that annealing after irradiation will reverse some of the rejuvenation that occurred from the irradiation. Preliminary neutron diffraction experiments conducted at the Spallation Neutron Source at ORNL indicate that the above may be true. These changes in the short-range ordering have also been shown to cause changes in the nanoindentation properties and soft-zone defect structure of BAM-11. However, further investigation is needed to better understand this phenomenon. Therefore, this project is expected to advance our knowledge of how atomic rearrangements induced by displacement cascades and annealing effect the mechanical and microstructural properties of amorphous alloy systems.Thus, the overarching scientific goal of our investigation is to observe and measure the effects of irradiation on the mechanical and microstructural properties of BAM-11 BMG. Specific technical objectives include the following: 1) Conduct 4-point bending tests using a MTS tensile screw-driven machine to examine the effects of neutron irradiation on the flexural stress-strain response of BAM-11. 2) Use a Keyence VHX-1000 digital microscope in conjunction with ImageJ software to characterize the fracture surface morphology of fracture bend test specimens. 3) Perform focused ion beam preparation of the neutron irradiated and post-annealed BAM-11 BMG. 4) Use transmission electron microscopy (TEM) to perform bright field imaging to characterize any deformation induced shear banding structure and to observe any irradiation induced observe any irradiation induced changes in short range ordering. 5) Use a Keysight Technologies G200 nanoindenter in conjunction with Berkovich and spherical tips to characterize any irradiation induced changes to nanoindentation and soft-zone defect properties of the alloy. The potential impact of this project on the scientific state of knowledge will be to quantify the effects of irradiation on the microstructural and mechanical properties of BAM-11 BMG, and in so doing, gain fundamental insight into the viability of amorphous alloys in nuclear reactor environments.
Additional Info
| Field | Value |
|---|---|
| Abstract | Recently, Zr based BMGs have been reported to have properties that are superior to that of conventional alloys, such as high strength and hardness, wear resistance, and corrosion resistance, which make it potentially suited for extreme environments. In addition, bulk metallic glasses are thought to have high helium permeability, due to their large free atomic volume and lack of grain boundaries which can act as helium traps. As such, this class of materials have been proposed as potential materials for nuclear applications. However, not much is known about the effects of neutron irradiation on the microstructure and mechanical properties of amorphous alloys. Therefore, the purpose of this investigation is to gain a more fundamental scientific understanding of the effects of irradiation displacement damage in a Zr based bulk metallic glass. It will be hypothesized here that neutron irradiation leads to structural rejuvenation in the BAM-11. Furthermore, it is believed that annealing after irradiation will reverse some of the rejuvenation that occurred from the irradiation. Preliminary neutron diffraction experiments conducted at the Spallation Neutron Source at ORNL indicate that the above may be true. These changes in the short-range ordering have also been shown to cause changes in the nanoindentation properties and soft-zone defect structure of BAM-11. However, further investigation is needed to better understand this phenomenon. Therefore, this project is expected to advance our knowledge of how atomic rearrangements induced by displacement cascades and annealing effect the mechanical and microstructural properties of amorphous alloy systems.Thus, the overarching scientific goal of our investigation is to observe and measure the effects of irradiation on the mechanical and microstructural properties of BAM-11 BMG. Specific technical objectives include the following: 1) Conduct 4-point bending tests using a MTS tensile screw-driven machine to examine the effects of neutron irradiation on the flexural stress-strain response of BAM-11. 2) Use a Keyence VHX-1000 digital microscope in conjunction with ImageJ software to characterize the fracture surface morphology of fracture bend test specimens. 3) Perform focused ion beam preparation of the neutron irradiated and post-annealed BAM-11 BMG. 4) Use transmission electron microscopy (TEM) to perform bright field imaging to characterize any deformation induced shear banding structure and to observe any irradiation induced observe any irradiation induced changes in short range ordering. 5) Use a Keysight Technologies G200 nanoindenter in conjunction with Berkovich and spherical tips to characterize any irradiation induced changes to nanoindentation and soft-zone defect properties of the alloy. The potential impact of this project on the scientific state of knowledge will be to quantify the effects of irradiation on the microstructural and mechanical properties of BAM-11 BMG, and in so doing, gain fundamental insight into the viability of amorphous alloys in nuclear reactor environments. |
| Award Announced Date | 2018-09-17T00:00:00 |
| Awarded Institution | None |
| Facility | None |
| Facility Tech Lead | Kory Linton |
| Irradiation Facility | None |
| PI | Steven Zinkle |
| PI Email | [email protected] |
| Project Type | RTE |
| RTE Number | 1469 |