Nuclear Science User Facilities 18 Dr. Cheng Sun RESEARCHER HIGHLIGHTS Dr. Cheng Sun, a staff scientist and principal investigator at Idaho National Labora- tory, studies materials irradiated in nuclear reactor environments. One of the biggest challenges guiding nuclear energy is the need to develop advanced materials that can better withstand harsh environments, like high temperatures and neutron/ion bombardment experienced inside a nuclear reactor. “We are performing fundamental understanding on the irradiation effects on reactor materials,” Sun said. “We hope we can design and develop advanced materials that can be used in reactors for longer service time.” Although his interest in nuclear energy research didn’t begin until he came to the United States to pursue a doctorate, Sun has always been inter- ested in how materials are formed and changed by their environment.As a child growing up in China, Sun never forgot an interesting grain texture revealed on the surface of a weathered stainless steel structure he once saw. When he began studying materials science and engineering in college, he came across the phenomenon again. “Crystalline metals have grain struc- tures,” Sun said. “I didn’t know what it was when I was a child, but later on I realized what I had seen.” Today, Sun continues pursuing that interest in materials science as he researches materials performance in extreme conditions. His research is focused on gaining a better under- standing of a material’s performance under extreme environments, with emphasis on the manufacturing- microstructure-mechanical property relationships of materials under irradiation. His primary areas of experimental expertise include additive manufacturing of nuclear materials, characterization of irradi- ated materials via electron microscopy and high-energy X-ray scattering, and small-scale mechanical testing of irradiated materials. Sun has worked at Idaho National Laboratory since 2016, when he arrived in Idaho as the first Russell L. Heath Distinguished Postdoctoral Associate.The Russell L. Heath post- doctoral appointment was established to attract, recruit, develop and inspire early career researchers who have the potential to develop into INL’s future scientific and technical leaders. At that time, INL’s manager of advanced characterization department, Dr. Jian Gan, said Sun’s proposal spoke for itself. “His impressive research achievements, supported by his strong publication record, make him a highly talented, early career researcher with great potential to make significant