Complex Systems under Extremes (DOE)

Assistant Professor Wen Chen and Associate Professor Jae-Hwang Lee of the Mechanical and Industrial Engineering (MIE) Department will  be “leads” on two of the five research teams in the newly funded Center for Additively Manufactured Complex Systems under Extremes (CAMCSE). Physics Professor Yogesh Vohra of the University of Alabama Birmingham (UAB) is the principal investigator for the $8-million center, as funded by the U.S. Department of Energy. In all, $1.8 million of that sum will come to Chen and Lee at UMass Amherst as part of a 17-member CAMCSE team that spans six disciplines across five core academic partners – UAB, UMass Amherst, Tuskegee University, Stanford University, and the University of California-Irvine.

Chen, the UMass Amherst principal investigator for the DoE center, will be one of two leads on the “Goal 1” team of CAMCSE: “Additive Manufacturing of Compositionally Complex Systems.” Meanwhile, Lee will serve as one of two leads for the “Goal 4” team: “Micro-ballistic Indentation of Compositionally Complex Systems.”

The mission of CAMCSE is to advance foundational discoveries in far-from-equilibrium complex systems under extreme strain rates while training the next generation of researchers in the field.

According to the proposal, “Over the last decade, a paradigm shift has occurred in materials science. The field has moved from traditional alloys and compounds to compositionally complex systems, such as high-entropy alloys, high-entropy metallic glasses, and composite materials. This shift has been complemented by parallel developments in additive manufacturing, which are in direct support of the DoE’s National Nuclear Security Administration’s (NNSA) Stockpile Stewardship Program and its efforts to reduce the time-to-product for nuclear weapons components, decrease the manufacturing footprint, and lessen waste.”

The proposal goes on to explain that “A central challenge is a lack of fundamental understanding of the response of additively manufactured compositionally complex systems under extreme environments (i.e., high pressure, high temperature, and high strain rates) that occur in the deployment of these materials in specific NNSA applications.”

That challenge is crucial because additively manufactured metal alloys are produced through highly localized melting processes, significant temperature gradients, and high cooling rates upon solidification during fabrication.

According to the proposal, “CAMCSE proposes to study the performance of additively manufactured compositionally complex systems over a broad range of extreme conditions to address key knowledge gaps.”

Lee, the head of the Nano-engineering Laboratory in the MIE department, will be one of two leaders in the fourth of the five CAMCSE goals: “multiscale micro-ballistic indentation of compositionally complex systems under high strain rates.”

To study this phenomenon, Lee and his colleagues will introduce a unique experimental framework called “micro-ballistic indentation” based on the UMass-created “laser-induced projectile impact test” (LIPIT). The pioneering test accelerates a single spherical ceramic impactor at a controlled temperature and provides the impactor’s kinetic-energy loss in collision with a specimen using ultrafast “stroboscopy.” Stroboscopy employs special instrumentation to make a cyclically moving object appear to be slow-moving or stationary.

As Lee and his colleagues indicate, “LIPIT is the most versatile micro-ballistic tool for extreme materials science and mechanics, providing high-strain-rate mechanical stimuli with highly accurate kinetic information within the ideal spatial scale for additively manufactured compositionally complex systems to cover multiscale microstructural phenomena.”

As UAB’s Vohra summarizes the new DoE center, “Our long-term goal is to gain fundamental understanding of far-from-equilibrium, compositionally complex alloys and glasses under high strain rates so they could be deployed in practice under extreme environments.” (August 2023)