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Yu Research Group

Yu Research Group

About Us

The Yu Research Group focuses on materials processing science in advanced manufacturing, emphasizing the underlying process physics, kinetics, and metallurgy. The Yu Research Group is recognized as a pioneer of solid-state metal additive manufacturing via additive friction stir deposition, which demonstrates salient advantages over mainstream fusion-based metal additive manufacturing in quality, properties, cost, energy consumption, and environmental impact. Additive friction stir deposition is characterized by rapid and large shear flow at elevated temperatures. Such intricate thermomechanical conditions provide a unique platform to investigate some peculiar intertwined kinetic phenomena, such as continuous dynamic recrystallization, shear-induced mixing and segregation on the atomic scale, and shear-induced fracture and dispersion on the micro- and meso-scale. 

Our research portfolio covers process fundamentals (temperature, material flow), dynamic phase and microstructure evolution mechanisms, design and manufacturing of heterostructured materials, and circular economy applications such as structural repair and recycling (and upcycling). Materials of interest include precipitate-strengthened alloys (e.g., aerospace grade 7xxx and 2xxx Aluminum), two-phase alloys (e.g., Ti-6Al-4V), pure metal (e.g., Cu), as well as functional materials, such as magnetic materials and shape memory alloys and composites. Non-conventional alloys of particular interest are driven alloys and intermetallic phases resulting from shear-induced mixing.

Through in situ and time-resolved characterization, we aim to develop an in-depth understanding of the underlying kinetics and evolution mechanisms and compare the findings with existing thermodynamic and kinetic frameworks, from which new theories may arise towards the creation of non-equilibrium, dynamic phase diagrams. With the gained process and metallurgical fundamentals, we seek to establish quantitative process-structures-property linkages and advance material sustainability through niche applications, e.g., solid-state rapid metal recycling, structural repair, and manufacturing in austere conditions. Future work involves the extension of the methodology to other solid-state processes, wherein more general mechanisms and criteria can be established for solid-state bonding, shedding light on emerging areas like multi-material solid-state metal additive manufacturing and heterogeneous integration via hybrid bonding. 

Through collaboration, we are also exploring process control of additive manufacturing enabled by the integration of in situ monitoring, physics simulation, and AI-based prediction.

* We are proud to share that Professor Hang Yu is honored to be a recipient of the DARPA (Defense Advanced Research Projects Agency) Young Faculty Award. In the capacity of the lead PI, Professor Hang Yu has been fortunate to receive a DURIP (Defense University Research Instrumentation Program) Award of $800,000. This generous grant enabled the acquisition and installation of a state-of-the-art MELD L3 metal 3D printer, further enhancing our research capabilities. Our research group is also actively involved in contributing to the development of the world's largest metal 3D printer, which is currently under construction at Rock Island Arsenal, IL.

*In addition to these exciting developments, Professor Hang Yu has recently published a monograph titled 'Additive Friction Stir Deposition' with Elsevier in 2022. Furthermore, he is collaborating with Dr. Nihan Tuncer (Desktop Metal) and Dr. Zhili Feng (Oak Ridge National Laboratory) to edit a forthcoming book titled 'Solid-State Metal Additive Manufacturing: Physics, Processes, Mechanical Properties, and Applications,' which is currently in the press with Wiley-VCH.

*We are delighted to share some articles highlighting the achievements of our research group. One article is titled 'Research and Industry Partnership Helps Forge 21st Century Metallurgy'.  Another article, published by the American Chemistry Society, is titled 'Metal 3D Printing Is Showing Its Mettle.' These articles provide insight into the impactful work our team is contributing to the field of metallurgy and 3D printing.




The Yu Research Group at Virginia Tech advocates for the simultaneous advancement of technology and society as crucial elements for a more promising future. The group is dedicated to upholding its core principles of amplifying their influence by actively addressing diversity, equity, and inclusion (DEI) within the engineering domain:

With unwavering commitment, our team endeavors to cultivate a constructive professional and social atmosphere that embraces individuals of all backgrounds and ensures their acceptance and respect, irrespective of their race, ethnicity, gender, country of origin, religion, sexual orientation, or skin color, while addressing the world's most pressing engineering needs.


Featured News

Recently students in the Yu research group worked to assist Virginia Tech's unprecedented COVID-19 response by 3D printing face shield bands and assisting in design of N-95 replacement masks. As a whole Virginia Tech delivered more than 2000 face shields to surrounding hospitals and is poised to deliver critical components if the need arises. 

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