I’m a second-year PhD student in the Materials Science and Engineering program at NC State. Originally from the Indian west coast state of Gujarat, I work in Dr. Kinga Unocic’s Extreme Environments and Advanced Characterization Lab. Our research focuses on studying the high-temperature oxidation performance of materials with novel microstructures and processing routes, as well as advanced in situ characterization leveraging transmission electron microscopy. My current project examines how additive manufacturing influences the high-temperature oxidation performance of the Ni-based superalloy Inconel 718. Outside the lab, I enjoy reading fiction and history, listening to and playing music, kayaking, and playing soccer.
What instruments are you using for your research and why do you like them?
Additively manufactured (AM), especially Laser Powder Bed Fusion (LPBF) alloys are known for their complex, metastable microstructures, which give rise to a range of interesting properties, some beneficial, others detrimental. These microstructures contain features spanning length scales from the SEM to the TEM level, so a multi-instrument approach is essential. I use the UHR SU8700 SEM to study features ranging from hundreds of microns down to roughly one micron. The Oxford Instruments EDS and EBSD detectors provide critical information about AM alloys, including grain structure, crystallographic texture and orientation, as well as macroscale elemental composition and segregation and second phase formation. However, stopping characterization at the SEM level can sometimes lead to incomplete or misleading conclusions, features unresolvable at that scale often play a decisive role in properties ranging from mechanical behavior to oxidation mechanisms. This is where the TEM becomes indispensable, unlocking, as Williams & Carter describe in their textbook, “the ability to understand and control matter at dimensions of roughly 1 to 100 nanometers.” Thin samples are prepared using Focused Ion Beam (FIB) from regions of interest. I currently use the Talos F2000 TEM, and soon, hope to be trained on the Spectra Ultra, to analyze nanoscale features. These include cellular structures in AM alloys via HRSTEM, elemental segregation via STEM-EDS using the SuperX quad EDS detectors, crystal structure identification through diffraction and FFT analysis and much more. Together, these techniques cover the full spectrum of microstructural length scales, from the microscale to the nanoscale, ensuring no critical information is overlooked and allow me to completely understand the processing-structure-property- relationships.
What have you been researching?
My current work investigates the effect of Laser Powder Bed Fusion (LPBF), an additive manufacturing technique, on the high-temperature oxidation mechanisms and kinetics of IN 718. The first objective is to study the influence of LPBF-induced cellular microstructures on oxidation behavior through conventional ex situ experiments under extreme and dynamic conditions, such as temperatures above 700 °C in various flowing gas environments or repeated thermal shock cycling. The second objective is to examine the role of nanoscale precipitates and directly observe the early stages of oxidation in LPBF IN 718 through in situ TEM oxidation experiments, enabled by the Protochips Atmosphere TEM holder.
High-temperature corrosion is an evergreen challenge that demands constant effort to mitigate and continues to define the boundaries of cutting-edge technology. Yet before meaningful solutions can be developed, it is essential to first build a fundamental understanding of the underlying mechanisms at play. With the state-of-the-art nanoscale characterization tools available at the AIF, it is possible to uncover phenomena that were previously either misunderstood or entirely unknown. This knowledge can then be leveraged to develop new materials or refine existing ones, enabling more capable and cost-effective technologies across the energy and transportation sectors.
What have you learned from your experience at AIF?
The AIF has been, and will continue to be, a central part of my research. I have gone from not knowing what the “T” in TEM stands for to independently operating state-of-the-art microscopes with confidence. Along the way, I have developed skills spanning the fundamentals of electron microscopy, the inner workings of TEM instrumentation, and strategies for analyzing and interpreting large, complex datasets accurately and efficiently.
Best thing about AIF in 5 words or less?
Cutting-edge, Convenient, Reliable & Supportive
Is there a staff member at AIF that has helped you?
Every AIF staff member has supported, helped, or trained me in some capacity, but I would like to give special thanks to Chris, for all things TEM; Chuck, for teaching me the ways of the SEM; Roberto, for his support with FIB work; Jenny, for helping me navigate XRD; Ruksana, for her assistance with XCT data analysis; and last but certainly not least, Toby, for knowing and helping with, quite literally, everything.
This post was originally published in Analytical Instrumentation Facility (AIF).