Advanced Characterization of Materials for Nuclear, Radiation, and Extreme Environments: Fusion Materials & In-Situ Ion Irradiation
Sponsored by: TMS Nuclear Materials Committee
Program Organizers: Samuel Briggs, Oregon State University; Christopher Barr, Department Of Energy; Emily Aradi, University of Huddersfield; Michael Short, Massachusetts Institute of Technology; Janelle Wharry, Purdue University; Cheng Sun, Clemson University; Dong Liu, University of Oxford; Khalid Hattar, University of Tennessee Knoxville
Tuesday 2:00 PM
November 3, 2020
Room: Virtual Meeting Room 13
Location: MS&T Virtual
Session Chair: Khalid Hattar, Sandia National Laboratories; Cheng Sun, Idaho National Laboratories
2:00 PM
Controlling Helium Morphology in Pure Metals: Effects of Helium Defects on Deformation and Strength: Calvin Lear1; Jonathan Gigax1; Nan Li1; Saryu Fensin1; 1Los Alamos National Laboratory
Prolonged irradiation of metal components results in the accumulation of excess microstructural defects, degradation of materials performance, and increased overall cost. Although the evolution of helium in structural materials is a crucial aspect of this problem, the impacts of helium morphology on materials strength are little understood beyond grain boundary effects. A systematic study of temperature-dose-dose rate interactions was thus performed in pure metals. The strength, ductility, and mode of deformation for helium implanted samples were probed using nanoindentation and micro-mechanical testing with in situ observation, while electron microscopy was used to investigate dislocation interactions with atomic clusters, spherical bubbles, and faceted bubbles of helium in the deformed samples. These findings are considered in terms of controlling helium defect nucleation and growth – and thus degradation – in metal components.
2:20 PM
Nanomechanical Change of Tungsten in ELM Conditions: Minsuk Seo1; Leigh Winfrey1; 1The Pennsylvania State University
Edge Localized Modes (ELMs) are one of the great concerns in the nuclear fusion reactor operation because of the heat loads of 1-10GW/m2 with microsecond pulsed plasma would thermally damage the plasma facing materials the brittle tungsten. Tungsten samples exposed to 12.5, 22.8, and 46.3GW/m2 heat flux were evaluated using nanonindentation to evaluate the nanomechanical behaviors in extreme environments. The results showed that the plasma peening like hardening effects appeared near the plasma contacting regions. Helium implantation may not be involved in the hardening because of the limited stopping range. However, a higher heat load softens the matrix due to the high temperature annealing as recovery temperature is easily achievable. Describing the competition of two factors in different heat loads along the depth dimension is important since the mass ablation of tungsten of lifetime relies on mechanical properties.
2:40 PM
Modified stereo TEM for 3D analysis of defects: Benjamin Eftink1; Stuart Maloy1; 1Los Alamos National Laboratory
Characterization of irradiation induced microstructural changes using TEM typically has the issue of analyzing 3D distributions of features in 2D. This is not effective, for example, when analyzing the correlation between precipitates and cavities or the character of dislocations. While there are traditional tomographic methods to extract the third spatial dimension of information, these require extensive data collection and reconstruction. A modified version of stereo-microscopy, developed at LANL, removes the traditional 3D tomography barriers by using a discrete-geometric approach using only two images to model microstructural features including precipitates, cavities, dislocations, and grain boundaries. This talk will present methodology and recently published applications of a modified stereo-TEM method to neutron irradiated HT-9 and tungsten alloys for nuclear environments.
3:00 PM Invited
Fundamental In-situ Experiments Coupled to High-throughput Approaches to Understand Radiation Damage in FCC and BCC Compositionally Complex Alloys: Adrien Couet1; Michael Moorehead1; Calvin Parkin1; Mohamed Elbakhshwan1; Hongliang Zhang1; Chuan Zhang2; Meimei Li3; Wei-Ying Chen3; Lin Shao4; Dan Thoma1; Kumar Sridharan1; 1University of Wisconsin-Madison; 2Computherm, LLC; 3Argonne National Laboratory; 4Texas A&M University
Compositionally Complex Alloys (CCAs) are multi-component alloys which have been reported to exhibit desirable mechanical and radiation-tolerant properties. While several CCAs have shown excellent phase stability and resistance to void swelling under irradiation, the origins of these properties are still under debate – further challenging CCA development. Indeed, while CCAs intrinsic radiation resistance properties have been hypothesized, few of them have been confronted to experimental validation. In addition, it is still unclear if these properties can be generalized across the extensive CCA composition fields. In light of this, FCC and BCC CCA fundamental radiation damage properties were investigated under cryo and high-temperature in-situ ion irradiation. Void swelling behavior was also studied under in-situ dual He beam implantation. To investigate if these properties can be generalized across the CCA composition field, high-throughput (i) synthesis, (ii) ion irradiation, (iii) characterization techniques have also been employed to accelerate CCA development for nuclear applications.
3:40 PM
Analysis of Heavy Ion Irradiation Damage in Commercially Pure Titanium and Titanium Alloys: Aida Amroussia1; Carl Boehlert1; Frederique Pellemoine2; Wolfgang Mittig3; David Grummon1; Thomas Bieler1; Clara Grygiel4; Meimei Li5; Wei-Ying Chen5; Isabelle Monnet4; 1Michigan State University; 2Faclity for Rare Isotope Beam - Michgan State University; 3National Superconducting Cyclotron Laboratory - Michigan State University; 4CIMAP; 5Argonne National Laboratory
Thanks to their good mechanical properties and low activation under irradiation, titanium alloys are selected for several applications in radioactive environments. The current study investigated the effect of ion irradiation damage on the microstructure and the nano-hardness in Ti and Ti alloys, namely commercially pure (CP) Ti and a two-phase α+β Ti-6Al-4V (wt.%) alloy processed through conventional powder metallurgy rolling (PM) and additive manufacturing (AM). Radiation hardening was observed in all materials irradiated ex situ at 30℃ and 360℃. A strong dose dependence was observed especially for the PM α+β Ti-alloy. The resistance to radiation hardening in the AM Ti-alloy was higher than that for the PM rolled alloy due to its lamellar microstructure. The radiation-induced dislocation loop evolution was investigated through in situ TEM irradiation at different temperatures in Ti and AM Ti-6Al-4V. The dispersed barrier hardening model was successfully used to analyze structure-mechanics relationships in irradiated CP Ti.
4:00 PM
In Situ Observation of Irradiation Damage in Polycrystalline Nuclear Graphite: Dong Liu1; David Cherns1; Joshua Kane2; Weiying Chen3; Steve Jones4; Karthik Chinnathambi4; William Windes2; 1University of Bristol; 2Idaho National Laboratory; 3Argonne National Laboratory; 4Boise State University
Understanding irradiation induced damage in nuclear graphite is of particular relevance to operating AGRs and some GenIV designs. Ex situ C+ implantation (Surrey Ion Beam Centre, UK) and in situ Ar+ irradiation (IVEM, ANL, USA) were used to simulate neutron damage over a range of temperatures up to 1000C. The surface morphological changes as well as residual stresses introduced by carbon ions were characterized and the decrease in crystallite size was compared to samples with the same neutron doses. It was found that large amount of porosity was introduced due to irradiation which has subsequently contributed to the volume change. The Ar+ irradiation carried out in situ within a TEM showed that basal plane dislocation movement was the primary cause of the macro-scale behavior. A novel mechanistic model was proposed based on these observations and it is considered to be applicable to all materials with nano-scale 2D graphite-like polycrystalline structures.