Revealing Hidden Instabilities at “Special” Grain Boundaries: Electron Microscopy Insights into Localized Precipitation and Degradation in Structural Alloys (13/10/25)
Speaker and Affliation:
Dr. Semanti Mukhopadhyay
Post Doctoral Research Associate, Pacific Northwest National Laboratory, Richland, WA, USA
When?
13th October, 2025 (Monday), 11.00 AM (India Standard Time)
Where
KPA Auditorium, Dept. of Materials Engineering, IISc, Bangalore
Abstract:
In Ni-based superalloys, coherent annealing twin boundaries (ATBs)—traditionally regarded as low-energy, inert interfaces—can undergo localized phase transformations that drive precipitate evolution. Using state-of-the-art multi-scale characterization, we directly reveal that these nominally benign boundaries become hotspots for coherent precipitate evolution. Moreover, this unexpected interfacial precipitation is accompanied by adjacent precipitate-free zones that promote intense strain localization under mechanical loading, ultimately leading to premature failure near the twin boundaries. These findings challenge the conventional perception of twin boundaries as benign, static features and provide a mechanistic understanding of how atomic-scale interface evolution can undermine macroscale alloy integrity. Finally, ongoing work extending these insights to environmental degradation (oxidation) along grain boundaries in adjacent structural alloys will also be discussed, underscoring the broader implications of interface-driven transformations for alloy performance.
Speaker Bio:
Dr. Semanti Mukhopadhyay is a metallurgical engineer specializing on understanding the materials behavior at atomic level utilizing cutting edge electron Microscopy tools. Her educational backgrounds include a Batchelor and Master’s degree (dual degree) from IIT Kanpur. She carried out his doctoral work at Ohio State University under the guidance of Professor M.J.Mill. Following her doctoral work, she is currently working at Pacific Northwest National Laboratory as a post-doctoral Research Associate at Physical and Computational Directorate.