Dr. Li He is an assistant scientist at the department of Engineering Physics, University of Wisconsin-Madison. She graduated from University of Virginia with Ph.D. in Materials Science and Engineering and conducted postdoc research at Rensselaer Polytechnic Institute and then UW-Madison. She specializes in nanoscale characterizations of advanced alloys and semiconductors using electron microscopy. Her current work includes ion irradiation and post-irradiation characterization of stainless steels and zirconium alloys for nuclear reactors.
|"Atomic Resolution Imaging of Black Spot Defects in Ion Irradiated Silicon Carbide" Li He, Hao Jiang, Yizhang Zhai, Cheng Liu, Izabela Szlufarska, Beata Tyburska-Puschel, Kumar Sridharan, Paul Voyles, Microscopy and Microanalysis Vol. 21 2015 1337-1338 Link|
"Effects of Al and Ti Additions on Irradiation Behavior of FeMnNiCr Multi-Principal-Element Alloy"
Andrew Hoffman, Haiming Wen, Li He, Kumar Sridharan, Matthew Luebbe, Jiaqi Duan,
Two Co-free multi-principal-element alloys (MPEAs), viz. single-phase face-centered cubic (FCC) Fe30Ni30Mn30Cr10 and (Fe30Ni30Mn30Cr10)94Ti2Al4 (all in atomic percent) with FCC matrix containing Ni-Ti-Al enriched L12 (ordered FCC) secondary phase (γ′), have been developed and investigated. The alloys were ion irradiated at 300°C and 500°C to peak damage of 120 displacements per atom (dpa). Compared with the (Fe30Ni30Mn30Cr10)94Ti2Al4 alloy, in the Fe30Ni30Mn30Cr10 alloy, the dislocation loops were smaller, with a higher number density. The difference in loop size between the two MPEAs was attributed to the addition of Ti to the matrix, which was anticipated to lower the stacking fault energy and stabilize the faulted Frank loops. The γ′ phase showed good stability under irradiation, with no new γ′ precipitation or growth in existing precipitates. Both alloys showed similar irradiation-induced hardening at 300°C, but the (Fe30Ni30Mn30Cr10)94Ti2Al4 alloy exhibited lower irradiation-induced hardening at 500°C compared with the Fe30Ni30Mn30Cr10 alloy.
|"Enhanced diffusion of Cr in 20Cr-25Ni type alloys under proton irradiation at 670 °C" Tianyi Chen, Ying Yang, Li He, Beata Tyburska-Puschel, Kumar Sridharan, Haixuan Xu, Lizhen Tan, Nuclear Materials and Energy Vol. 17 2018 142-146 Link|
"Enhanced Resistance to Irradiation Induced Ferritic Transformation in Nanostructured Austenitic Steels"
Andrew Hoffman, Maalavan Arivu, Haiming Wen, Li He, Kumar Sridharan, Xin Wang, Xiang Liu, Lingfeng He, Yaqiao Wu,
Irradiation induced phase transformation of γ-austenite to α-ferrite has been observed in austenitic steels for the past several decades. This transformation can be detrimental to structural materials in a nuclear reactor environment as the increased fraction of the ferritic phase can increase corrosion and embrittlement and lead to stress corrosion cracking. This transformation is caused by both strain induced martensite transformation as well as radiation induced segregation and precipitation. In this study, two radiation tolerant nanostructured 304L austenitic steels (one ultrafine grained and one nanocrystalline) were manufactured using severe plastic deformation. These nanostructured 304L steels were compared to conventional coarse-grained 304L, after self-ion irradiation at 500°C up to a peak damage of 50 displacements per atom. Phase fraction after irradiation was analyzed using grazing incidence x-ray diffraction, precession electron diffraction, and electron backscatter diffraction. Nanostructured 304L steels showed significant resistance to irradiation induced austenite to ferrite transformation. This resistance was shown to be due to a decrease in defect formation, as well as a reduction in radiation induced segregation and precipitation.
|"Evolution of small defect clusters in ion-irradiated 3C-SiC: Combined cluster dynamics modeling and experimental study" Cheng Liu, Li He, Yizhang Zhai, Beata Tyburska-Puschel, Paul Voyles, Kumar Sridharan, Dane Morgan, Izabela Szlufarska, Acta Materialia Vol. 125 2017 377-389 Link|
|"High-Resolution Scanning Transmission Electron Microscopy Study of Black Spot Defects in Ion Irradiated Silicon Carbide" Li He, Yizhang Zhai, Cheng Liu, Chao Jiang, Izabela Szlufarska, Beata Tyburska-Puschel, Kumar Sridharan, Paul Voyles, Microscopy and Microanalysis Vol. 20 2014 1824-1825 Link|
|"Measurement of Irradiation-induced Swelling in Stainless Steels with a New Transmission Electron Microscopy Method" Li He, Haixuan Xu, Lizhen Tan, Paul Voyles, Kumar Sridharan, Microscopy and Microanalysis Vol. 23 2017 2234-2235 Link|
|"Microstructural evolution in Fe-20Cr-25Ni austenitic alloys under proton irradiation at 670 ºC" Tianyi Chen, Lizhen Tan, Li He, Beata Tyburska-Puschel, Kumar Sridharan, Transactions of American Nuclear Society Vol. 117 2017 581-583 Link|
|"Radiation-induced mobility of small defect clusters in covalent materials" Hao Jiang, Li He, Dane Morgan, Paul Voyles, Izabela Szlufarska, Physical Review B Vol. 94 2016 024107 Link|
|"Size distribution of black spot defects and their contribution to swelling in irradiated SiC" Beata Tyburska-Puschel, Yizhang Zhai, Li He, Cheng Liu, Alexandre Boulle, Paul Voyles, Izabela Szlufarska, Kumar Sridharan, Journal of Nuclear Materials Vol. 476 2016 132-139 Link|
|"Structural Evolution of Oxidized Surface of Zirconium-Silicide under Ion Irradiation" Hwasung Yeom, Li He, Robert Mariani, Kumar Sridharan, Applied Surface Science Vol. 455 2018 333-342 Link|
|"Effects of Ti and Al Additions on Irradiation Behavior of FeMnNiCr Based High Entropy Alloys" Andrew Hoffman, Haiming Wen, Li He, Kumar Sridharan, 2019 TMS Annual Meeting March 10-14, (2019)|
|"Effects of Ti and Al Additions on Irradiation Behavior of FeMnNiCr Based High-Entropy Alloys" Matthew Luebbe, Andrew Hoffman, Hans Pommeranke, Li He, Kumar Sridharan, Haiming Wen, Materials Science & Technology 2019 September 29-3, (2019)|
|"Heat treatment Effects on Precipitation in Irradiated HT9 Steel" Theresa Mary Green, Li He, Todd Allen, MiNES (Materials in Nuclear Energy Systems) 2019 October 6-10, (2019)|
|"Ion Irradiation Defects in Austenitic Alloy 709 and Ferritic-Martensitic Steel Grade 92 for Nuclear Applications" Li He, Rigen Mo, Beata Tyburska-Puschel, Kumar Sridharan, Haixuan Xu, Tianyi Chen, Lizhen Tan, MRS Spring 2017 April 17-21, (2017)|
|"Ion irradiation for nuclear materials research at University of Wisconsin-Madison" Li He, Gabriel Meric, Kim Kriewaldt, Kumar Sridharan, Adrien Couet, Todd Allen, The 51st Symposium of the North Eastern Accelerator Personnel September 23-27, (2018)|
|"Microstructure Evolution in Dual Ion irradiated HT9 at 445 C and 460 C to 16.6 dpa" Li He, Theresa Mary Green, Todd Allen, MiNES (Materials in Nuclear Energy Systems) 2019 October 6-10, (2019)|
|"Poster - Examining microstructural differences in irradiated HT9 correlated with differences in processing prior to irradiation" Theresa Mary Green, Li He, Todd Allen, Brandon Miller, Lingfeng He, NUMAT 2018 October 15-18, (2018)|
|"Study of B2 and Laves Phase E volution in a Novel Ferr itic Steel under Ion Irradiation" Li He, Lizhen Tan, Ying Yang, Kumar Sridharan, MiNES (Materials in Nuclear Energy Systems) 2019 October 6-10, (2019)|
|"Study of gamma irradiation effect on the corrosion of zirconium alloy with scanning precession electron diffraction" Li He, Adrien Couet, Samuel Armson, Michael Preuss, Kurt Terrani, Midwest Microscopy and Microanalysis Society Meeting 2019 May 22-22, (2019)|
|"The Effect of Photon Irradiation on the Corrosion of Zirconium Alloys" Adrien Couet, Yalong He, Kurt Terrani, Samuel Armson, Michael Preuss, Taeho Kim, Mohamed Elbakhshwan, Li He, The 19th International Symposium on Zirconium in the Nuclear Industry May 20-23, (2019)|