Back in the early days of his college career, Chad Parish realized his curiosity and interests were drawing him to the type of work he performs today in the Low Activation Materials Development and Analysis, or LAMDA, laboratory at the Department of Energy's Oak Ridge National Laboratory. Using microscopy and microstructural characterization, he reveals the intricate atomic structures of materials essential for developing safer and more economical nuclear reactors. His talents and expertise place him at the center of many collaborations that pertain to materials for extreme environments and national security.
"A lot of people from all branches of the lab will come to me when they have a particularly hard problem, and I'll just do a one-off and help them. This has been my bread and butter for about a decade, and it has led to many long-term collaborations, too," said Parish, an ORNL senior research and development staff member.
As a child, Parish always loved the physical sciences. "My interests wandered around from week to week," he said. "They would go from chemistry to physics to paleontology, but I was always focused on some sort of science. I was terrible at sports."
Surrounded by older siblings and cousins, he was regularly watching their behaviors and picking up their books and interests, such as computer programming. "My young interest in computers didn't turn into my career, but it definitely became an advantage for me as a physical scientist," Parish said.
Because he'd taken Advanced Placement chemistry in high school, chemical engineering seemed like a good fit for his major because he was about to begin pursuing a bachelor's degree at North Carolina State University. But before the school would allow freshmen to choose their majors, it required them to visit different engineering programs. One that Parish visited was materials science and engineering.
"They were doing things like breaking big chunks of metal and putting materials under the electron microscope. The zoom knob went click, click, click, and tiny details were coming into view. I thought, 'This is it. This is my stuff right here,'" he said.
The informal materials science phrases for the entire process he observed that day are "heat and beat" or "cook and look" metallurgy. The experimenter makes the metal red hot, deforms it, and then records the distribution of properties across the material after heating and cooling. Parish would find himself applying such skills during his master's studies at the University of Pittsburgh. In research funded by U.S. Steel, he explored ways of optimizing the galvanizability of steel for the automotive industry.
"If the steel in your car isn't galvanized, it will rust from the salt used after the first snowstorm," Parish said. "No matter how good the properties of the steel are, the automotive industry won't adopt it if it can't achieve a perfect zinc galvanizing coating to prevent corrosion. We used trial and error with different alloying elements to strike a balance between good mechanical properties and galvanizability. From those experiments, I learned a great deal about electron microscopy, which I didn't realize at the time would become my specialty."
Establishing a career trajectory
In a significant departure from automotive steels, Parish next focused on optoelectronic devices, such as the light-emitting diodes used in modern lighting, while pursuing his doctorate back at North Carolina State University.
"We needed detectors to go inside the scanning electron microscope to interrogate materials, so I spent three and a half years in a basement lab at the university, elbow-deep in electron microscopes. The experience played an important part in establishing my career trajectory," he said.
The next phase of his developmental journey began when Sandia National Laboratories - which conducts national security research, including in areas such as nuclear deterrence, nonproliferation and advanced technologies for defense - hired him to interrogate data as a postdoctoral scholar.
"During my two and a half years at Sandia, I was able to apply many of the programming skills I picked up as a kid to the datasets from modern electron microscopes," Parish said. "In that way, two things of very different origins in my life merged not only to help me with the Sandia research but also to prepare me for some of the needs ORNL had at the time."
Parish joined ORNL in 2009 as an Alvin M. Weinberg Fellow, a program for early-career scientists and engineers who show exceptional research potential. Weinberg Fellows conduct independent projects in energy, environmental science or advanced technology while collaborating with experienced researchers and using ORNL's resources to advance their skills and careers.
"In my first couple of years at ORNL, I studied nuclear materials. I also examined topics as diverse as welding and solar cells," Parish said. "Coincidentally, several retirements were taking place when I was hired, and so I found myself needing to add techniques to my research repertoire, which consisted mostly of transmission electron microscopy and scanning electron microscopy. So, I learned how to leverage new skills with my existing ones and combine different experiments to answer questions."
Influencing fusion and fission materials research
Parish received the DOE Office of Science Early Career Research Program award for Fusion Energy Sciences in 2015. The award provided funding for him to address challenges in materials for nuclear fusion power. In 2018, he was chosen for the David J. Rose Excellence in Fusion Engineering award from Fusion Power Associates.
"If a space reentry vehicle and a nuclear reactor had a baby, it would be a fusion reactor," Parish said. "It's the most hideous service environment envisioned by the human mind. Every horrible thing is inside - plasma, neutrons, heat flux, magnetic fields and corrosive coolants."
ORNL has the largest fusion materials program in the United States. Parish has been helping and participating in that program for a long time because so much of materials science, and specifically nuclear materials, happens at the nanoscale.
"Say someone's invented a new steel and believes it's going to be wicked good as a structural material for a fusion reactor blanket module. Then it's cooked in a reactor for a year and turns out to be terrible," Parish said. "I can look at the microstructure and the nanostructure and determine what happened. I may find that the steel's recipe had too much carbon and grew chromium carbide on the grain boundaries, which became weak and caused the material to fail."
Parish has also lent his expertise to nuclear fission energy programs. He explained that much of the focus of the U.S. nuclear energy program since the 2011 meltdown of the Fukushima reactor in Japan has been on developing accident-tolerant materials.
"A lot of the research is directed at modeling nuclear fuels to discover what happens during a loss-of-coolant accident like at Fukushima," Parish said. "The evolution of the material can't be modeled unless the starting microstructure is known. That's the kind of information I'm giving them, and we're doing exciting research with wide implications."
Tapping into complementary strengths
Collaboratively, Parish and his ORNL research teammates work with many professors and their associated groups at the University of Tennessee. Several of the professors are joint faculty with ORNL. The ORNL fusion program also has strong ties with Stony Brook University in New York and the University of California, San Diego.
"Stony Brook does alloy design and materials processing that complement our electron microscopy and radiation materials science expertise," Parish said. "At San Diego, they're specialists in plasma-materials interaction, and my microstructural analysis explains phenomena in their plasma devices. Collaborations should always be with those who complement your expertise."
A ready resource for problem-solving
Day to day, people show up on Parish's doorstep when they're stumped - the experiments they've run or the people they've asked haven't determined what a particular material is.
"Because I bring a different toolbox to many of the problems, I can find a solution. For example, I may discover a key chemical interaction at a material interface, and then the person realizes the observation makes sense," Parish said. "What I bring to the table is that I'm reasonably good at several different things, which makes me well positioned as a crosscutting problem solver."
UT-Battelle manages ORNL for the Department of Energy's Office of Science, the single largest supporter of basic research in the physical sciences in the United States. The Office of Science is working to address some of the most pressing challenges of our time. For more information, please visit energy.gov/science . - Scott Gibson
