Jessica receives the GE fellowship in recognition of her excellent leadership, outreach service, and research capability. Many congratulations!!!
Author: Lee, Seok-Woo
Tyler’s paper was published at Journal of Materials & Design!
Tyler’s paper was published at Journal of Materials and Design! Many Congratulations! This work is the collaboration with multiple groups (Mark Aindow (UConn), Avinash Dongare (UConn), Cyril Williams (US Army Research Laboratory)).
Tyler J. Flanagan, Sriram Vijayan, Sergey Galitskiy, Jacob Davis, Benjamin Bedard, Avinash Dongare, Mark Aindow, Cyril L. Williams, Seok-Woo Lee, “Shock-induced deformation twinning and softening in magnesium single crystals,” 194, 108884, Materials & Design (2020) [PDF] [web]
Abstract
Magnesium is widely regarded as an excellent structural material, primarily because it forms the basis for a range of light-weight high-strength alloys. Recently, high-strain rate deformation of magnesium has received a great deal of attention due to the complicated deformation modes that involve combinations of dislocation slip and deformation twinning. In this study, single crystal magnesium samples were shock-compressed along the c- and a-axis, then released back to ambient conditions. Post-mortem transmission electron microscopy revealed that extension twins developed for both c- and a-axis shock loading. Also, the nanoindentation hardness values for these shocked samples were compared to those for samples compressed under quasi-static conditions; it was found that the hardness decreased with increasing strain rate for both c- and a-axis loading. Molecular dynamics simulations were performed to elucidate the detailed mechanisms of deformation twinning in terms of inertial confinement of sample geometry and different stress relaxation speed between impact and lateral directions. The conversion from work-done to heat was discussed to explain the influence of shock-induced heating on the residual hardness. These results give new insights into the residual mechanical response in shock-compressed materials and may help to develop a more fundamental understanding of shock phenomena in metallic materials.
Jessica’s paper was published at Journal of Materials & Design!
Jessica’s paper was published at Journal of Materials & Design. Many Congratulations!!!
- Jessica M. Maita, Gyuho Song, Mariel Colby, Seok-Woo Lee, “Atomic arrangement and mechanical properties of amorphous boron,” – Materials & Design, 193, 108856 (2020) [PDF] [web]
Abstract
Amorphous boron can be synthesized by chemical vapor deposition (CVD) onto a tungsten wire substrate, and this core-shell fiber has been widely used in high-performance composites due to its superior mechanical properties. Although the amorphous boron coating makes a significant contribution to the high fracture strength, its mechanical properties have not been studied rigorously due to its thin thickness and strong adhesion to the substrate. Furthermore, the medium-range atomic ordering of CVD amorphous boron has not been clearly understood, and the determination of the closest crystalline structure has been a challenge. In this study, high-resolution transmission electron microscopy (HRTEM), nanoindentation, and in-situ micropillar compression were performed to investigate the atomic arrangement and mechanical properties. Electron diffraction and autocorrelation function analysis revealed α-rhombohedral boron ordering as the closest crystalline structure. Micropillar compression displayed near-ideal yield strength (~13 GPa), but nanoindentation a relatively moderate Young’s modulus (~320 GPa), leading to a modulus of resilience (2.64 × 108 J/m3) unprecedentedly higher than most advanced engineering materials. Our structural and mechanical data will be discussed in terms of lattice point spacing and the influence of surface defects on fracture strength, respectively. Our results will be potentially useful to improve mechanical properties of amorphous boron core-shell fibers and related composites.
Beautiful artwork from DMD: Rotating Tyler’s Au microparticles!
This is the the artwork of UConn Digital Media and Design (DMD) Graduate Assistants Yucheng Hang, 杭雨城, and Maria Raykova. In an art-meets-science partnership, Yucheng and Maria created imaginative designs based on microscopy images provided by UConn Tech Park – Innovation Partnership Building researchers.
Artist’s Statement
This is my second piece of artwork in this series connecting the micro world with the macro world. The geometry of the original image inspired me to animate it and create a feeling of being in the universe. -Yucheng Chang
Original Image (displayed in comments below): solid-state de-wetted gold microparticles on sapphire substrate. Courtesy of Tyler Flanagan, CAMMA, IPB at UConn Tech Park.
The official link of this video is the following.
https://www.linkedin.com/feed/update/urn:li:activity:6664174078837968896/
Kiera attended the virtual Frontiers 2020!
Kiera participated in the virtual Frontiers 2020!
The title of her poster is “Effects of Alloying on Dislocation Nucleation in [001] SrNi2P2“. Kiera used spherical indentation and investigated the dislocation nucleation stress for differently alloyed SrNi2P2. She discovered that a large atomic inclusion (Rh) can induce a residual shear stress that lowers a dislocation nucleation stress. So, alloying has been known to make the motion of dislocation difficult, but it could the nucleation of dislocation easy!
Her online poster presentation is available at this Portfolium link. You must log-in with your UConn ID (or google/Facebook) to see her presentation.
Frontiers in Undergraduate Research exhibitions provide opportunities for UConn’s talented undergraduate researchers to share their work with the university community. Consistent with the University’s steps to prevent the spread of COVID-19, Frontiers 2020 has moved online.
Previously, Amanda Giroux (2018, currently at Electric Boat) and Hetal Patel (2019, currently at UC Berkeley) attended this event from our group. Kiera Burns is the third one (2020)! I am very proud of the excellence of our UConn undergraduate students!
Jessica receives the outstanding leadership award!
UConn MSE department gives the outstanding leadership award to a graduate student annually. This year, Jessica is selected. Many congratulations!!!
This is the second one from our research group! (after Gyuho!).
Jessica’s leadership is highlighted in MSE webpage!
Jessica has made a great contribution to MSE department as well as our local society. Her great leadership is highlighted in MSE webpage. It is a great article!
MSE Graduate Student Reaches Out to Help High Schoolers Transition to College
Gyuho passed his PhD defense! Super-Congratulations!
MSE department highlights Seok-Woo’s research and teaching!
Seok-Woo’s research and teaching is highlighted at the MSE Department News.
Shuyang participated in UConn SoE poster presentation (3/11/2020)!
Shuyang participated in UConn SoE poster presentation on 03/11/2020. The presentation title was “Mechanical behavior of uniaxial compression of SrNi2P2“.
This work discussed his recent experimental results on the ultrahigh superplastic strain and fatigue resistance in SrNi2P2 intermetallic compounds. SrNi2P2 shows 18% of elastic strain and survives over 10,000 cycles of superelastic deformation! Double lattice collapse is the main mechanism of superplasticity. This is certainly a new discovery!