NSUF 25-5313: Investigation of Elastic Interactions and Mechanical Behaviors in NF709 Using Coherence Enhanced High Energy Diffraction Microscopy

Irradiation introduces various defects into the lattice, which interact with existing dislocation structures and influence the overall defect network. These interactions significantly affect the mechanical and chemical properties of nuclear materials. A novel characterization framework, combining High Energy Diffraction Microscopy (HEDM) and Bragg Coherent Diffraction Imaging (BCDI), named Coherence Enhanced High Energy Diffraction Microscopy (CE-HEDM), can non-destructively characterize and visualize the elastic interactions in nuclear materials across an unprecedented range of scales in 3D. HEDM is a widely used 3DXRD technique that provides detailed information about polycrystals, such as grain shape, position, crystal orientation, and strain, all with meso-scale resolution. BCDI, another diffraction technique, is sensitive to atomic-scale displacements within lattices, allowing visualization of 3D details about elastic strain fields associated with the entire network of defects, including dislocations. Moreover, the transition from the mesoscale to sub-nano scale on mechanical behaviors can be guided by crystal plasticity finite element (CPFE) simulation in the combined framework. We propose to study the effects of irradiation on mechanical property in greater detail using the CE-HEDM framework by focusing on grains that provide the most differentiation between different material models for competing radiation hardening and local softening effects. Specifically, we will simulate the material response with several competing models to identify the critical grains that best differentiate those models during an in situ HEDM experiment. We will then compare the associated interactions of dislocations with the intragranular strain fields using BCDI to test those models and their underlying hypotheses. We will conduct in situ loading experiments with interrupted HEDM and BCDI measurements on neutron-irradiated and unirradiated NF709 tensile samples, well past their respective yield stress, pausing at multiple load levels to acquire 3D diffraction data. We will exploit the Activated Materials Laboratory (AML) facility located at APS to handle the irradiated samples.

Additional Info

Field	Value
Awarded Institution	Argonne National Laboratory
DOI	10.46936/NSUF/60015342
Embargo End Date	2027-09-03
Facility Tech Lead	Wei-Ying Chen
NSUF Call	FY 2025 RTE 2nd Call
PI	Seunghee Oh
PIE Facilities	Activated Materials Laboratory-Advanced Photon Source (1-ID, 20-ID beamlines)
Project Member	Dr. Seunghee Oh, Postdoctoral appointee - Argonne National Laboratory (https://orcid.org/0000-0002-6979-3235)
Project Type	RTE