Author: Lee, Seok-Woo

Zhongyuan gave an oral presentation at MRS Fall 2021!

Zhongyuan gave an oral presentation at MRS Fall 2021!

This presentation discusses the unique microstructures created by sequential infiltration of nanoscale oxide into SU-8 negative photoresist, which is used for MEMS structures. These Nanocomposites materials exhibit ultrahigh modulus of resilience (200 MJ/m^3), which is much higher than any other engineering materials. Their high modulus of resilience results from metal-like high strength but polymer-like low Young’s modulus. This unusual combination is potentially useful for developing a strong-but-flexible material that can be used for flexible display.

 

Farewell Lunch with Gyuho!

Gyuho will leave this Friday to California to start his new position at the Frore Systems. He will work as a material engineer to develop the Micro-electro-mechanical-system (MEMS) device that cools the high performance CPU much faster than the conventional technologies. Best wishes for his success in Silicon Valley!

Shuyang’s paper is published at Nano Letters! Many Congratulations!!!

Shuyang’s first paper is published at Nano Letters! Many congratulations! The paper is now available online [web]. This work discusses the unique pseudoelasticity mechanisms, double lattice and collapse due to the a solid-state bonding and debonding.

Shuyang Xiao, Vladislav Borisov, Guilherme Gorgen-Lesseux, Sarshad Rommel, Gyuho Song, Jessica M. Maita, Mark Aindow, Roser Valentí, Paul Canfield, Seok-Woo Lee, “Pseudoelasticity of SrNi2P2 micropillar via lattice collapse and expansion,” Nano Letters (2021) [Arxiv] [web

Abstract: The maximum recoverable strain of most crystalline solids is less than 1% because plastic deformation or fracture usually occurs at a small strain. In this work, we show that a SrNi2P2 micropillar exhibits pseudoelasticity with a large maximum recoverable strain of ∼14% under uniaxial compression via unique reversible structural transformation, double lattice collapse–expansion that is repeatable under cyclic loading. Its high yield strength (∼3.8 ± 0.5 GPa) and large maximum recoverable strain bring out the ultrahigh modulus of resilience (∼146 ± 19 MJ/m3), a few orders of magnitude higher than that of most engineering materials. The double lattice collapse–expansion mechanism shows stress–strain behaviors similar to that of conventional shape-memory alloys, such as hysteresis and thermo-mechanical actuation, even though the structural changes involved are completely different. Our work suggests that the discovery of a new class of high-performance ThCr2Si2-structured materials will open new research opportunities in the field of pseudoelasticity.

 

 

Tyler passed his PhD defense! Many Congratulations!

Tyler passed his PhD Defense! Many Congratulations, Dr. Flanagan!

Tyler recently accepted the job offer from the Evans Analytical Group (EAG) in the middle of Silicon Valley at California, where I spent my first five years in US. I wish he continues to make a great success in a new place. Congratulations! Yeah!

Seok-Woo gave two invited talks (KITECH and Korea University)!

Seok-Woo gave two invited talks. The title of talk was “Superelasticity of ThCr2Si2-structured intermetallic compounds: Making and Breaking Bonds“. These talks summarized our research on superplasticity of ThCr2Si2-structure intermetallic compounds for the past five years at UConn.

One invited talk was given at Korea Institute of Industrial Technology on August 11, and the other was given as the Department Seminar in the Department of Materials Science and Engineering at Korea University on August 18,