Meimei Li

Profile Information

Name: Meimei Li
Institution: Argonne National Laboratory
Expertise: Material Characterization

Publications:

		"9R phase enabled superior radiation stability of nanotwinned Cu alloys via in situ radiation at elevated temperature" Cuncai Fan, Dongyue Xie, Jin Li, Zhongxia Shang, Youxing Chen, Sichuang Xue, Jian Wang, Meimei Li, Anter EL-AZAB, Haiyan Wang, Xinghang Zhang, Acta Materialia Vol. 167 2019 248-256 Link
		"An in situ study on Kr ion–irradiated crystalline Cu/amorphous-CuNb nanolaminates" Zhe Fan, Cuncai Fan, Jin Li, Zhongxia Shang, Sichuang Xue, Marquis Kirk, Meimei Li, Haiyan Wang, Xinghang Zhang, Journal of Materials Research Vol. 2019 1-11 Link
		"Characterization of neutron-irradiated HT-UPS steel by high-energy X-ray diffraction microscopy" Xuan Zhang, Jun-Sang Park, Jonathan Almer, Meimei Li, Journal of Nuclear Materials Vol. 471 2016 280-288 Link This paper presents the first measurement of neutron-irradiated microstructure using far-field high-energy X-ray diffraction microscopy (FF-HEDM) in a high-temperature ultrafine-precipitate-strengthened (HT-UPS) austenitic stainless steel. Grain center of mass, grain size distribution, crystallographic orientation (texture), diffraction spot broadening and lattice constant distributions of individual grains were obtained for samples in three different conditions: non-irradiated, neutron-irradiated (3dpa/500 °C), and irradiated + annealed (3dpa/500 °C + 600 °C/1 h). It was found that irradiation caused significant increase in grain-level diffraction spot broadening, modified the texture, reduced the grain-averaged lattice constant, but had nearly no effect on the average grain size and grain size distribution, as well as the grain size-dependent lattice constant variations. Post-irradiation annealing largely reversed the irradiation effects on texture and average lattice constant, but inadequately restored the microstrain.
		"Effects of neutron irradiation and post-irradiation annealing on the microstructure of HT-UPS stainless steel" Chi Xu, Wei-Ying Chen, Xuan Zhang, Meimei Li, Yong Yang, Yaqiao Wu, Journal of Nuclear Materials Vol. 507 2018 188-197 Link Microstructural changes resulted from neutron irradiation and post-irradiation annealing in a high-temperature ultra-fine precipitate strengthened (HT-UPS) stainless steel were characterized using transmission electron microscopy (TEM) and atom probe tomography (APT). Three HT-UPS samples were neutron-irradiated to 3 dpa at 500?°C, and after irradiation, two of them were annealed for 1?h?at 600?°C and 700?°C, respectively. Frank dislocation loops were the dominant defect structure in both the as-irradiated and 600?°C post-irradiation-annealed (PIAed) samples, and the loop sizes and densities were similar in these two samples. Unfaulted dislocation loops were observed in the 700?°C PIAed sample, and the loop density was greatly reduced in comparison with that in the as-irradiated sample. Nano-sized MX precipitates were observed under TEM in the 700?°C PIAed sample, but not in the 600?°C PIAed or the as-irradiated samples. The titanium-rich clusters were identified in all three samples using APT. The post-irradiation annealing (PIA) caused the growth of the Ti-rich clusters with a stronger effect at 700?°C than at 600?°C. The irradiation caused elemental segregations at the grain boundary and the grain interior, and the grain boundary segregation behavior is consistent with observations in other irradiated austenitic steels. APT results showed that PIA reduced the magnitude of irradiation induced segregations.
		"High-energy synchrotron x-ray techniques for studying irradiated materials" David Hoelzer, Jun-Sang Park, Xuan Zhang, Hemant Sharma, Peter Kenesei, Meimei Li, Jonathan Almer, Journal of Materials Research Vol. 30 2015 1380-1391 Link High performance materials that can withstand radiation, heat, multiaxial stresses, and corrosive environment are necessary for the deployment of advanced nuclear energy systems. Nondestructive in situ experimental techniques utilizing high energy x-rays from synchrotron sources can be an attractive set of tools for engineers and scientists to investigate the structure-processing-property relationship systematically at smaller length scales and help build better material models. In this study, two unique and interconnected experimental techniques, namely, simultaneous small-angle/wide-angle x-ray scattering (SAXS/WAXS) and far-field high-energy diffraction microscopy (FF-HEDM) are presented. The changes in material state as Fe-based alloys are heated to high temperatures or subject to irradiation are examined using these techniques.
		"High-energy x-ray diffraction microscopy study of deformation microstructures in neutron-irradiated polycrystalline Fe-9%Cr, " Xuan Zhang, Meimei Li, Jun-Sang Park, Peter Kenesei, Hemant Sharma, Jonathan Almer, Journal of Nuclear Materials Vol. 508 2018 556-566 Link In this study, we used far-field high-energy x-ray diffraction microscopy (FF-HEDM) to measure in 3D the spatial distributions of the sizes, orientations, and residual strains of grains and subgrains formed by room-temperature tensile deformation in a neutron-irradiated (450?°C, 0.01dpa) Fe-9Cr specimen and its unirradiated counterpart. We found that neutron irradiation under this condition alone had no effect on the grain size distribution. After deformation, grains fragmented into subgrains in both unirradiated and irradiated specimens: the irradiated specimen contained a few large subgrains which co-existed with many smaller subgrains, while the unirradiated specimen contained small subgrains with a relatively uniform size distribution. Prior to deformation, the irradiated specimen had higher residual strain spread compared to its unirradiated counterpart, while after deformation to the maximum uniform elongation, the strain distributions among subgrains were similar between the unirradiated and irradiated specimens. The FF-HEDM measurements provide new insight into the effects of neutron irradiation on the mechanical response of Fe-Cr ferritic alloys.
		"In situ Evidence of Defect Cluster Absorption by Grain Boundaries in Kr Ion Irradiated Nanocrystalline Ni" Kaiyuan Yu, Youxing Chen, Marquis Kirk, Haiyan Wang, Meimei Li, Xinghang Zhang, Metallurgical and Materials Transactions A Vol. 44 2013 1966 Link Significant microstructural damage, in the form of defect clusters, typically occurs in metals subjected to heavy ion irradiation. High angle grain boundaries (GBs) have long been postulated as sinks for defect clusters, like dislocation loops. Here, we provide direct evidence, via in situ Kr ion irradiation within a transmission electron microscope, that high angle GBs in nanocrystalline (NC) Ni, with an average grain size of ~55 nm, can effectively absorb irradiation-induced dislocation loops and segments. These high angle GBs significantly reduce the density and size of irradiation-induced defect clusters in NC Ni compared to their bulk counterparts, and thus NC Ni achieves significant enhancement of irradiation tolerance.
		"In situ high-energy X-ray diffraction study of tensile deformation of neutron-irradiated polycrystalline Fe-9%Cr alloy" Meimei Li, James Stubbins, Chi Xu, Xuan Zhang, Jun-Sang Park, Peter Kenesei, Jonathan Almer, Acta Materialia Vol. 126 2017 67-76 Link The effect of neutron irradiation on tensile deformation of a Fe-9wt%Cr alloy was investigated using in situ high-energy synchrotron X-ray diffraction during room-temperature uniaxial tension tests. New insights into the deformation mechanisms were obtained through the measurements of lattice strain evolution and the analysis of diffraction peak broadening using the modified Williamson-Hall method. Two neutron-irradiated specimens, one irradiated at 300 °C to 0.01 dpa and the other at 450 °C to 0.01 dpa, were tested along with an unirradiated specimen. The macroscopic stress–strain curves of the irradiated specimens showed increased strength, reduced ductility and reduced work-hardening exponent compared to the unirradiated specimen. The evolutions of the lattice strain, the dislocation density and the coherent scattering domain size in the deformation process revealed different roles of the submicroscopic defects in the 300 °C/0.01 dpa specimen and the nanometer-sized dislocation loops in the 450 °C/0.01 dpa specimen; the dislocation loops were more effective in dislocation pinning. While the work hardening rate of stage II was unaffected by irradiation, significant dynamic recovery in stage III in the irradiated specimens led to the early onset of necking without stage IV as observed in the unirradiated specimen.
		"In situ microstructural evolution in face-centered and body-centered cubic complex concentrated solid-solution alloys under heavy ion irradiation" Michael Moorehead, Calvin Parkin, Mohamed Elbakhshwan, Jing Hu, Wei-Ying Chen, Meimei Li, Lingfeng He, Kumar Sridharan, Adrien Couet, Acta Materialia Vol. 198 2020 85-99 Link This study characterizes the microstructural evolution of single-phase complex concentrated solid- solution alloy (CSA) compositions under heavy ion irradiation with the goal of evaluating mecha- nisms for CSA radiation tolerance in advanced fission systems. Three such alloys, Cr 18 Fe 27 Mn 27 Ni 28 , Cr 15 Fe 35 Mn 15 Ni 35 , and equimolar NbTaTiV, along with reference materials (pure Ni and E90 for the Cr- FeMnNi family and pure V for NbTaTiV) were irradiated at 50 K and 773 K with 1 MeV Kr ++ ions to vari- ous levels of displacements per atom (dpa) using in-situ transmission electron microscopy. Cryogenic irra- diation resulted in small defect clusters and faulted dislocation loops as large as 12 nm in face-centered cubic (FCC) CSAs. With thermal diffusion suppressed at cryogenic temperatures, defect densities were lower in all CSAs than in their less compositionally complex reference materials indicating that point defect production is reduced during the displacement cascade stage. High temperature irradiation of the two FCC CSA resulted in the formation of interstitial dislocation loops which by 2 dpa grew to an average size of 27 nm in Cr 18 Fe 27 Mn 27 Ni 28 and 10 nm in Cr 15 Fe 35 Mn 15 Ni 35 . This difference in loop growth kinet- ics was attributed to the difference in Mn-content due to its effect on the nucleation rate by increasing vacancy mobility or reducing the stacking-fault energy.#171118
		"In situ Observation of Defect Annihilation in Kr Ion-Irradiated Bulk Fe/Amorphous-Fe2 Zr Nanocomposite Alloy" Kaiyuan Yu, Zhe Fan, Youxing Chen, Miao Song, Yue Liu, Haiyan Wang, Mark Kirk, Meimei Li, Xinghang Zhang, Materials Research Letters Vol. 3 2014 35 Link
		"In situ studies of Kr ion irradiation response of Fe/Y2O3 nanolayers" Youxing Chen, Liang Jiao, Cheng Sun, Miao Song, Kaiyuan Yu, Yue Liu, Meimei Li, Haiyan Wang, Xinghang Zhang, Journal of Nuclear Materials Vol. 452 2014 321 Link
		"In situ studies on radiation tolerance of nanotwinned Cu" Youxing Chen, Jin Li, Kaiyuan Yu, Haiyan Wang, Meimei Li, Xinghang Zhang, Acta Materialia Vol. 111 2016 148 Link
		"In situ Study of Defect Migration Kinetics and Self-Healing of Twin Boundaries in Heavy Ion Irradiated Nanotwinned Metals" Jin Li, Kaiyuan Yu, Youxing Chen, Miao Song, Haiyan Wang, Mark Kirk, Meimei Li, Xinghang Zhang, Nano Letters Vol. 15 2015 2922 Link
		"In situ study of defect migration kinetics in nanoporous Ag with enhanced radiation tolerance" Cheng Sun, Youxing Chen, Yongqiang Wang, Meimei Li, Haiyan Wang, Xinghang Zhang, Scientific Report Vol. 4 2014 Link
		"In-situ high-energy X-ray characterization of neutron irradiated HT-UPS stainless steel under tensile deformation" Chi Xu, Xuan Zhang, Yiren Chen, Meimei Li, Jun-Sang Park, Peter Kenesei, Jason Almer, Yong Yang, Acta Materialia Vol. 156 2018 330-341 Link The tensile deformation behavior of a high-temperature, ultrafine-precipitate strengthened (HT-UPS) stainless steel was characterized in-situ with high-energy X-ray diffraction at 20 and 400?°C. The HT-UPS samples were neutron irradiated to 3 dpa at 400?°C. Significant irradiation hardening and ductility loss were observed at both temperatures. Lattice strain evolutions of the irradiated samples showed a strong linear response up to near the onset of the macroscopic yield, in contrast to the unirradiated HT-UPS which showed a pronounced non-linear behavior well below the macroscopic yield. While the room-temperature diffraction elastic moduli in the longitudinal direction increased after irradiation, the 400?°C moduli were similar before and after irradiation. The evolution of the {200} lattice strain parallel to the loading axis () showed unique characteristics: in the plastic regime, the evolution of after yield is temperature-dependent in the unirradiated specimens but temperature-independent in the irradiated specimens; and the value of at the yield is an irradiation-sensitive, temperature-independent parameter. The evolution of corresponds well with the dislocation density evolution, and is an effective probe of the deformation-induced long-range internal stresses in the HT-UPS steel.
		"In-situ observation of nano-oxide and defect evolution in 14YWT alloys" Osman El Atwani, Meimei Li, Stuart Maloy, Eda Aydogan, Materials Characterization Vol. 170 2020 110686 Nanostructured ferritic alloys (NFAs) are considered as candidates for structural components in advanced nuclear reactors due to their excellent radiation resistance as a result of a high density of nano-oxides (NOs) in the microstructure. Therefore, gaining an understanding on the stability of NOs under irradiation is crucial. In this study, we have investigated the evolution of defects and NOs in 14YWT NFAs under in-situ Kr ion irradiation at room temperature (RT) and 450 °C up to 10 dpa. It has been found that irradiations at 450 °C do not create any changes in the NOs, similar to the bulk irradiations. On the other hand, elemental mapping indicates that NOs dissolve mostly after 10 dpa irradiations at RT. Thus, while defects are both annihilated and pinned by NOs at low doses (before the dissolution of NOs), glissile loops start to escape to the foil surface at high doses (after the dissolution of NOs), justifying the significantly low fraction of <111> loops compared to the literature values. High resolution transmission electron microscopy analysis has shown that the NOs are mostly coherent Y2Ti2O7 particles with pyrochlore crystal structure after both RT and 450 °C irradiations, similar to those observed before irradiation.
		"In-situ radiation response of additively manufactured modified Inconel 718 alloys" Eda Aydogan, Osman El Atwani, Begum Erdem, Wei-Ying Chen, Meimei Li, ARUN DEVARAJ, Bahattin Koc, Stuart Maloy, Additive Manufacturing Vol. 51 2022 102601 In this study, a novel alloy of modified Inconel 718 produced by laser powder bed fusion is studied before and after in-situ Kr irradiation up to 3 dpa at 200 and 450 °C. Before irradiation, the microstructure consists of dislocation cells having a misorientation angle less than 5° and with an average size of ~500 nm. There are also second phase particles of MC type carbides, Laves phase and oxides such as Y-O, Y-(Ti)-Al-O. While the microstructure consists of stacking fault tetrahedra, faulted and perfect loops after irradiation at 200 °C, dislocation loops are the primary defects at 450 °C. With increasing dose, the size of the defects remains similar at 200 °C while it increases at 450 °C. This has been attributed to the existence of vacancy type defects at 200 °C and the different defect transport mechanisms at different temperatures. Moreover, matrix and second phase particle compositions seem to be similar after irradiation. The sink strengths of the structures have been calculated and superior radiation resistance of this alloy has been attributed to the existence of fine cell boundaries stabilized by the second phase particles produced by additive manufacturing.
		"In-situ TEM study of microstructural evolution in NFA and Cr3C2@SiC-NFA composite during ion irradiation" Kathy Lu, Xianming Bai, Wei-Ying Chen, Meimei Li, Kaustubh Bawane, Materialia Vol. 7 2019 12 Link In this work, the ion irradiation responses of a Fe-based nanostructured ferritic alloy or ‘NFA’ (Fe–9Cr–2W–0.2V–0.4Ti–0.3Y2O3) and a Cr3C2@SiC-NFA composite were assessed. In-situ ion irradiation with TEM observation was carried out by using 1 MeV Kr++ ions at doses of 0, 1, 3, 5, 10 dpa and temperatures of 300 °C and 450 °C. Both the NFA and Cr3C2@SiC-NFA samples showed significant dislocation density after 10 dpa at 300 °C. However, the Cr3C2@SiC-NFA composite showed a significantly lower dislocation loop density and a smaller average loop size during the irradiation at 450 °C as opposed to the NFA. At 300 °C, 1/2<111> type dislocation loops were observed in both the NFA and Cr3C2@SiC-NFA samples. Interestingly, at 450 °C, <100> type loops were dominant in the NFA sample while 1/2<111> type loops were still dominant in the Cr3C2@SiC-NFA sample. The results were discussed based on the large surface sink effects and enhanced interstitial-vacancy recombination at higher temperatures. The additional Si element in the Cr3C2@SiC-NFA sample might have played a significant role in determining the dominant loop types.
		"Ion-irradiation-induced microstructural modifications in ferritic/martensitic steel T91" Xiang Liu, Yinbin Miao, Meimei Li, Marquis Kirk, Stuart Maloy, James Stubbins, Journal of Nuclear Materials Vol. 490 2017 305-316 Link In this paper, in situ transmission electron microscopy investigations were carried out to study the microstructural evolution of ferritic/martensitic steel T91 under 1 MeV Krypton ion irradiation up to 4.2 × 1015 ions/cm2 at 573 K, 673 K, and 773 K. At 573 K, grown-in defects are strongly modified by black-dot loops, and dislocation networks together with black-dot loops were observed after irradiation. At 673 K and 773 K, grown-in defects are only partially modified by dislocation loops; isolated loops and dislocation segments were commonly found after irradiation. Post irradiation examination indicates that at 4.2 × 1015 ions/cm2, about 51% of the loops were type for the 673 K irradiation, and the dominant loop type was for the 773 K irradiation. Finally, a dispersed barrier hardening model was employed to estimate the change in yield strength, and the calculated ion data were found to follow the similar trend as the existing neutron data with an offset of 100–150 MPa.
		"Irradiation-induced amorphization in the zirconium suboxide on Zr-0.5Nb alloys" Junliang Liu, Guanze He, Jing Hu, Zhao Shen, Mark Kirk, Meimei Li, Ed Ryan, Pete Baldo, Sergio Lozano-Perez, Chris Grovenor, Journal of Nuclear Materials Vol. 513 2018 226 - 231 We report for the first time the observation of irradiation-induced amorphization of the zirconium suboxide formed during aqueous corrosion of Zr-0.5Nb alloys. High-resolution transmission electron microscopy results reveal amorphization of the hexagonal-ZrO suboxide under heavy ion irradiation at cryogenic temperatures. This irradiation-induced amorphization behaviour is discussed in relation to the arrangement of oxygen interstitials and the formation of stable superlattices. The sensitivity of the suboxide to irradiation damage can lead to phase changes and the accumulation of defects near the oxide/metal interface, which needs to be taken into account in the development of mechanistic models addressing radiation-assisted acceleration of corrosion rates in zirconium alloys.
		"Measurement of heavy ion irradiation induced in-plane strain in patterned face-centered-cubic metal films: an in situ study" Kaiyuan Yu, Youxing Chen, Jin Li, Yue Liu, Haiyan Wang, Meimei Li, Xinghang Zhang, Nano Letters Vol. 16 2016 7481–7489 Link
		"Microstructural evolution of neutron-irradiated T91 and NF616 to ~4.3 dpa at 469 °C" Kevin Field, Bong Goo Kim, Lizhen Tan, Yong Yang, Sean Gray, Meimei Li, Journal of Nuclear Materials Vol. 493 2017 12-20 Link Ferritic-martensitic steels such as T91 and NF616 are candidate materials for several nuclear applications. This study evaluates radiation resistance of T91 and NF616 by examining their microstructural evolutions and hardening after the samples were irradiated in the Advanced Test Reactor to ∼4.3 displacements per atom (dpa) at an as-run temperature of 469 °C. In general, this irradiation did not result in significant difference in the radiation-induced microstructures between the two steels. Compared to NF616, T91 had a higher number density of dislocation loops and a lower level of radiation-induced segregation, together with a slightly higher radiation-hardening. Unlike dislocation loops developed in both steels, radiation-induced cavities were only observed in T91 but remained small with sub-10 nm sizes. Other than the relatively stable M23C6, a new phase (likely Sigma phase) was observed in T91 and radiation-enhanced MX → Z phase transformation was identified in NF616. Laves phase was not observed in the samples.
		"Microstructural evolution of NF709 (20Cr–25Ni–1.5 MoNbTiN) under neutron irradiation" Bong Goo Kim, Lizhen Tan, Yong Yang, Cheryl Xu, Xuan Zhang, Meimei Li, Journal of Nuclear Materials Vol. 470 2016 229-235 Link Because of its superior creep and corrosion resistance as compared with general austenitic stainless steels, NF709 has emerged as a candidate structural material for advanced nuclear reactors. To obtain fundamental information about the radiation resistance of this material, this study examined the microstructural evolution of NF709 subjected to neutron irradiation to 3 displacements per atom at 500 °C. Transmission electron microscopy, scanning electron microscopy, and high-energy x-ray diffraction were employed to characterize radiation-induced segregation, Frank loops, voids, as well as the formation and reduction of precipitates. Radiation hardening of ∼76% was estimated by nanoindentation, approximately consistent with the calculation according to the dispersed barrier-hardening model, suggesting Frank loops as the primary hardening source.
		"Predicting neutron damage using TEM with in situ ion irradiation and computer modeling" Brian Wirth, Donghua Xu, Marquis Kirk, Meimei Li, Journal of Nuclear Materials Vol. 498 2018 199-212 Link We have constructed a computer model of irradiation defect production closely coordinated with TEM and in situ ion irradiation of Molybdenum at 80 °C over a range of dose, dose rate and foil thickness. We have reexamined our previous ion irradiation data to assign appropriate error and uncertainty based on more recent work. The spatially dependent cascade cluster dynamics model is updated with recent Molecular Dynamics results for cascades in Mo. After a careful assignment of both ion and neutron irradiation dose values in dpa, TEM data are compared for both ion and neutron irradiated Mo from the same source material. Using the computer model of defect formation and evolution based on the in situ ion irradiation of thin foils, the defect microstructure, consisting of densities and sizes of dislocation loops, is predicted for neutron irradiation of bulk material at 80 °C and compared with experiment. Reasonable agreement between model prediction and experimental data demonstrates a promising direction in understanding and predicting neutron damage using a closely coordinated program of in situ ion irradiation experiment and computer simulation.
		"Radiation induced detwinning in nanotwinned Cu" Youxing Chen, Haiyan Wang, Meimei Li, Jian Wang, Xinghang Zhang, Scripta Materialia Vol. 130 2017 37-41 Link
		"Radiation induced nanovoid shrinkage in Cu at room temperature: An in situ study" Cuncai Fan, Annadanam Sreekar, Zhongxia Shang, Jin Li, Meimei Li, Haiyan Wang, Anter EL-AZAB, Xinghang Zhang, Scripta Materialia Vol. 166 [unknown] 112-116 Link
		"Radiation resistance of oxide dispersion strengthened alloys: Perspectives from in situ observations and rate theory calculations" Xiang Liu, Yinbin Miao, Meimei Li, Marquis Kirk, Guangming Zhang, Shigeharu Ukai, Stuart Maloy, James Stubbins, Scripta Materialia Vol. 148 2018 33-36 Link Here, in situ ion irradiation and rate theory calculations were employed to directly compare the radiation resistance of an oxide dispersion strengthened alloy with that of a conventional ferritic/martensitic alloy. Compared to the rapid buildup of dislocation loops, loop growth, and formation of network dislocations in the conventional ferritic/martensitic alloy, the superior radiation resistance of the oxide dispersion strengthened alloy is manifested by its stable dislocation structure under the same irradiation conditions. The results are consistent with rate theory calculations, which show that high-density nanoparticles can significantly reduce freely migrating defects and suppress the buildup of clustered defects.
		"Removal of stacking-fault tetrahedra by twin boundaries in nanotwinned metals" Kaiyuan Yu, Cheng Sun, Yue Liu, Haiyan Wang, Mark Kirk, Meimei Li, Xinghang Zhang, Nature Communications Vol. 4 2013 Link
		"Resilient ZnO nanowires in an irradiation enviroment: an in situ study" Cheng Sun, Jin Li, Youxing Chen, Mark Kirk, Meimei Li, Stuart Maloy, Haiyan Wang, Xinghang Zhang, Acta Materialia Vol. 95 2015 156 Link
		"Study of Irradiated Mod. 9Cr-1Mo Steel by Synchrotron XAS" Hasitha Ganegoda, Daniel Olive, Jeff Terry, Yulia Trenikhina, Meimei Li, Stuart Maloy, Transactions of the American Nuclear Society Vol. 102 2010 855 Link
		"Study of irradiated mod.9Cr–1Mo steel by synchrotron extended X-ray absorption fine structure" Hasitha Ganegoda, Meimei Li, Stuart Maloy, Jeff Terry, Yulia Trenikhina, Daniel Olive, Journal of Nuclear Materials Vol. 441 2013 674-680 Link Synchrotron extended X-ray absorption fine structure (EXAFS) spectroscopy measurements were performed to study the dose dependence of and alloying effects on irradiation-induced changes in the local atomic environments in a mod.9Cr–1Mo ferritic-martensitic steel. The measurements were carried out at room temperature on non-irradiated and irradiated specimens exposed to 1, 4, and 10 displacement per atom (dpa) at 40–70 °C. The EXAFS data for Fe, Cr, Mo, and Nb K-edges were recorded, and the local structure close to the X-ray absorbing atom was determined. Irradiation caused significant reductions in peak amplitude in the Fe, Mo and Nb K-edge Fourier transformed EXAFS. The data showed a systematic decrease in coordination number of neighbor atoms with increasing irradiation dose, and the dose dependence of the coordination loss was dependent on the specific element. The measured damage around Fe sites can be correlated with the dpa value, while the loss of near neighbors around Mo saturated at ~1 dpa. The coordination in the Fe matrix was reduced less by irradiation than either the coordination of Mo in solution or Nb in carbides. It was demonstrated that EXAFS can provide a detailed, atomic level description of radiation damage in complex alloy systems
		"Unravelling Irradiation-Induced Detwinning Mechanisms via In Situ and Aberration-Corrected TEM combined with Atomistic Simulations" Pranav Kumar Suri, James Nathaniel II, Meimei Li, Mitra Taheri, Microscopy and Microanalysis Vol. Suppl 1 2018 1926-1927 Link

Presentations:

	"In Situ Dual-Beam Ion Irradiation with Transmission Electrom Microscopy" Meimei Li, Jing Hu, ANS Annual Meeting 2018 June 15-18, (2018)
	"In-Situ Synchrotron X-Ray Scattering Study on the Tensile Properties of Neutron Irradiated Ferritic/ Martensitic Alloys" Xiang Liu, Kuan-Che Lan, Meimei Li, Xuan Zhang, Chi Xu, James Stubbins, ANS Annual Meeting 2018 June 11-22, (2018)
	"Microstructural Characterization of High-entropy Alloy Ion Irradiated at Cryogenic Temperatures" Michael Moorehead, Calvin Parkin, Lingfeng He, Jing Hu, Meimei Li, Adrien Couet, Kumar Sridharan, TMS 2019 March 10-14, (2019)
	"Radiation response of nanostructured austenitic stainless steels " Zhongxia Shang, Cuncai Fan, Jin Li, Tongde Shen, Yinmin Morris Wang, Marquis Kirk, Meimei Li, Haiyan Wang, Xinghang Zhang, 2019 ANS & TMS MiNES meeting October 7-10, (2019)

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Study of an Irradiated Ferritic Steel by Synchrotron XRD and XAS - FY 2010 APS, #230

Synchrotron X-ray Diffraction Study of Microstructural Evolution in Irradiated Mod.9Cr-1Mo Steel - FY 2011 APS, #264

TBD - FY 2018 CINR, #4615

NSUF Research Collaborations

Alumina-stabilized coatings under irradiations: towards future generation nuclear systems - FY 2019 RTE 3rd Call, #2890

An in-situ TEM characterization of tensile testing of ion irradiated HT-UPS steel at RT and 400°C - FY 2017 RTE 3rd Call, #1098

Characterize Neutron Irradiated HT-UPS Stainless Steel Using Transmission Electron Microscopy and Atom Probe Tomography - FY 2016 RTE 1st Call, #622

Characterize Neutron Irradiated NF709 Stainless Steel Using Atom Probe Tomography - FY 2015 RTE 3rd Call, #591

Effect of Neutron Irradiation on Tensile Deformation of a HT-UPS Stainless Steel - FY 2016 RTE 2nd Call, #643

Effects of helium on the defect accumulation under ion implantation in a Fe-9Cr alloy - FY 2020 RTE 2nd Call, #4159

In situ ion irradiation and high resolution microstructure and microchemistry analysis of accident tolerant fuels - FY 2017 RTE 1st Call, #870

Innovations in Austenitic Manganese Steels for Nuclear Applications: Insights from In-Situ TEM Irradiation Experiments at the IVEM Facility - FY 2024 RTE 1st Call, #4875

Investigation of the Tensile-Deformed Microstructure of a Neutron-Irradiated Type 316 Stainless Steel Specimen - FY 2018 RTE 3rd Call, #1520

Radiation-induced Crystallization in Alumina Coatings: Temperature and Yttria Doping Effect. A Completion Kinetic Study to Model Radiation Resistant Coatings for the Future Nuclear System. - FY 2021 RTE 1st Call, #4255

Study of the behavior under ion irradiation of amorphous oxide protective coatings developed for lead fast reactors - FY 2024 RTE 1st Call, #4889

Study on defect evolution and stability of Y-Ti-O nano-oxides in 14YWT alloys under heavy ion irradiation - FY 2018 RTE 2nd Call, #1434

Meimei Li

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