NSUF 16-656: TEM in situ microcantilever testing of irradiated F/M alloys
The objective of this project is to acquire a multiscale mechanistic understanding of grain boundary cohesion and fracture in irradiated ferritic/martensitic (F/M) alloys, through transmission electron microscopic (TEM) in situ cantilever testing. F/M steels are candidates for cladding and structural components of advanced nuclear reactors. It is well known, however, that these materials exhibit grain boundary radiation-induced segregation (RIS) of Cr and minor alloying elements. RIS changes the grain boundary cohesive energy, which consequently affects the fracture behavior of the material. This is an inherently multiscale problem, as RIS is a point defect-driven process, grain boundary cohesion a microscale challenge, and fracture a macroscopic consequence. Previously, RIS and fracture experiments had to be conducted ex situ. Now, TEM mechanical testing enables in situ testing of RIS, crack propagation, and fracture. Thus, we hypothesize that TEM in situ microcantilever tests are the ideal tool for understanding fracture mechanisms across the length scales. In this work, we propose to conduct TEM in situ microcantilever tests of three irradiated commercial F/M alloys T91, HCM12A, and HT9. We will observe and record video of crack propagation. Grain boundary RIS measurements will connect the cracking to atomistic models of grain boundary chemistry and cohesion. Microcantilever tests will also generate load-displacement-time data that can be used to calculate cohesive laws governing macroscopic fracture. In summation, this experimental approach will link atomic, micro, and macro length scales, providing tremendous insight into the mechanisms governing fracture of irradiated F/M alloys. This work will also provide validation for finite element models in MOOSE.
Additional Info
| Field | Value |
|---|---|
| Abstract | The objective of this project is to acquire a multiscale mechanistic understanding of grain boundary cohesion and fracture in irradiated ferritic/martensitic (F/M) alloys, through transmission electron microscopic (TEM) in situ cantilever testing. F/M steels are candidates for cladding and structural components of advanced nuclear reactors. It is well known, however, that these materials exhibit grain boundary radiation-induced segregation (RIS) of Cr and minor alloying elements. RIS changes the grain boundary cohesive energy, which consequently affects the fracture behavior of the material. This is an inherently multiscale problem, as RIS is a point defect-driven process, grain boundary cohesion a microscale challenge, and fracture a macroscopic consequence. Previously, RIS and fracture experiments had to be conducted ex situ. Now, TEM mechanical testing enables in situ testing of RIS, crack propagation, and fracture. Thus, we hypothesize that TEM in situ microcantilever tests are the ideal tool for understanding fracture mechanisms across the length scales. In this work, we propose to conduct TEM in situ microcantilever tests of three irradiated commercial F/M alloys T91, HCM12A, and HT9. We will observe and record video of crack propagation. Grain boundary RIS measurements will connect the cracking to atomistic models of grain boundary chemistry and cohesion. Microcantilever tests will also generate load-displacement-time data that can be used to calculate cohesive laws governing macroscopic fracture. In summation, this experimental approach will link atomic, micro, and macro length scales, providing tremendous insight into the mechanisms governing fracture of irradiated F/M alloys. This work will also provide validation for finite element models in MOOSE. |
| Award Announced Date | 2016-04-11T00:00:00 |
| Awarded Institution | Idaho National Laboratory |
| Facility | Advanced Test Reactor |
| Facility Tech Lead | Alina Zackrone, Kory Linton, Kumar Sridharan, Tarik Saleh, Thomas Hartman, Yaqiao Wu |
| Irradiation Facility | None |
| PI | Janelle Wharry |
| PI Email | [email protected] |
| Project Type | RTE |
| RTE Number | 656 |