The PI is organizing and hosting the OSU MatSci seminars (ME 507) this fall (2022), which are a series of weekly Zoom-talks by eight of our distinguished guests from world-leading institutions. The Abstract and Speaker's Bio for each seminar will be posted here one week in advance. 

(Last year we had the pleasure of hosting Dr. Douglas Hofmann (NASA-JPL), Prof. Jan Schroers (Yale University) and Prof. William D. Nix (Stanford University))

 

*********************************** 9/29/2022 seminar ***********************************

From clusters to fractal packing: Unravel the mystery in atomic structure of amorphous solids and liquids

Prof. Mo Li 

School of Materials Science and Engineering

Georgia Institute of Technology

Thursday, September 29, 2022

4:00-4:50 pm Pacific Time

Abstract: 

Structure-property relation is a foundation of materials science and engineering. Atomic structure is at the center of this endeavor that guides and helps material design, processing, application, and basic scientific understanding of material properties. We are truly fortunate to be able to "see" atomic structures in crystalline materials where Bragg diffraction is made possible by the periodic atomic packing. In amorphous solids, the structural disorder is down to the atomic scale that has prevented us from observing atomic structure. As a result, the important structure-property relation has remained a mystery up to date.

In this talk, I will review two widely accepted hypotheses of atomic packing in metallic glasses, one is the atomic cluster packing and the other the fractal packing. These two proposed atomic structures cover the short- and medium-range ordering with universality across many materials systems. Here I will show that neither the cluster nor the fractal packing is convincingly rooted in physics. For example, the icosahedral cluster is found not to be the local atomic packing with the lowest energy as previously thought, and the fractal packing does not exist at all. 

These contradicting finding, however, does not solve the issues of the atomic structure, instead pose more questions to us. In this talk, I will explain the reasons and arguments behind our findings and pose new questions that may inspire students and researchers to join the work for discovery of the atomic structure of amorphous solids and liquids.

Bio:

Professor Mo Li received his B.S, in materials science from Central South University in China and Ph.D. in applied physics from Caltech. After a brief staying as a postdoctoral fellow at Caltech and the Argonne National Laboratory, he joined the investment bank Morgan Stanley & Co. in New York. He came back to academia in 1998. From 1998 to 2001, he was an assistant professor at the Johns Hopkins University. Currently, he is a professor at the Georgia Institute of Technology. He is the recipient of the National Thousands Talent Program Award of China and the Alexander von Humboldt Young researcher award. 

Professor Li's research focuses on understanding fundamental properties and processes of materials, and predicting material behaviors. The approaches used in his research are a blend of those from statistical physics, solid state physics, materials science, metallurgy, mechanics and large scale, high performance computing. His research focuses on algorithm development, simulation, and theoretical analysis.

 

*********************************** 10/6/2022 seminar ***********************************

An overview of the mechanical properties of metallic glasses

Prof. Frans Spaepen 

School of Engineering and Applied Sciences

Harvard University

Thursday, October 6, 2022

4:00-4:50 pm Pacific Time

Abstract: 

After a brief review of the thermodynamics and kinetics of glass formation, the mechanical behavior of metallic glasses will be surveyed using the stress-temperature deformation mechanism map, covering  elastic and anelastic deformation, homogeneous and inhomogeneous flow, brittle and ductile fracture, and the effects of structural relaxation.  The microscopic basis of plastic deformation is the presence of localized shear transformation zones, the action of which creates a characteristic strain pattern in the surrounding elastic matrix.  Deformation experiments on colloidal glasses can be used to identify those zones directly.

Bio:

Frans Spaepen is the Franklin Professor of Applied Physics in the School of Engineering and Applied Sciences at Harvard University.  He obtained his undergraduate degree in metallurgical engineering from the University of Leuven in 1971, and his Ph.D. in applied physics from Harvard in 1975, where he has remained ever since.  He has been Director of the Materials Research Science and Engineering Center (1990-1998) and of the Rowland Institute (2002-2013), and Interim Dean of the School of Engineering (2008-09).  His research interests span a wide range of experimental and theoretical topics in materials science, such as amorphous metals and semiconductors (viscosity, diffusion, mechanical properties), the structure and thermodynamics of interfaces (crystal/melt, amorphous/crystalline semiconductors, grain boundaries), mechanical properties of thin films, and colloidal systems as models for the study of dynamics and defects in crystals and glasses. Professor Spaepen is a member of National Academy of Engineering. 

 

*********************************** 10/13/2022 seminar ***********************************

Atomic Dynamics in Energy Materials: Vibrations, Diffusion, and Phase 

Prof. Olivier Delaire

Department of Mechanical Engineering and Materials Science

Duke University

Thursday, October 13, 2022

4:00-4:50 pm Pacific Time

Abstract: 

Investigating atomic motions in solids is critical to refine microscopic theories of transport and thermodynamics, in order to design improved materials. For instance, understanding the dynamics of ions is key to rationalize functional properties in numerous materials, ranging from superionic diffusion for solid-state batteries, to phase transitions and electron-phonon coupling in metal-halide perovskites, as well as nanoscale thermal transport in thermoelectrics for cooling or waste-heat harvesting. Yet, textbook models of atomic vibrations (phonons) often fall short in real materials, hindering material design. For instance, near phase transitions associated with lattice instabilities, strong anharmonic effects disrupt the conventional quasiharmonic phonon gas model. Large vibrational amplitudes, for example in crystals with soft bonds, also renormalize the electronic structure via the electron-phonon interaction. To reveal and clarify the ionic configurations and motions in real materials, our group uses state-of-the-art neutron and x-ray scattering techniques. Further, we perform first-principles simulations augmented with machine-learning algorithms to rationalize scattering experiments and identify underlying principles and descriptors enabling the design of future materials. This presentation will highlight the importance of investigating complex ion dynamics in several classes of materials, including halide perovskite photovoltaics [1], thermoelectrics [2,3], and superionic conductors [4,5,6].

[1] T. Lanigan-Atkins*, X. He* et al. "Two-dimensional overdamped fluctuations of soft perovskite lattice in CsPbBr3", Nature Materials 20, 977-983 (2021), https://doi.org/10.1038/s41563-021-00947-y

[2] J. Ding et al. "Anharmonic phonons and origin of ultralow thermal conductivity in Mg3Sb2 and Mg3Bi2", Science Advances 7:eabg1449 (2021). https://doi.org/10.1126/sciadv.abg1449

[3] T. Lanigan-Atkins*, S. Yang* et al. "Extended anharmonic collapse of phonon dispersions in SnS and SnSe", Nature Communications 11, 1-9 (2020). https://doi.org/10.1038/s41467-020-18121-4   

[4] J. L. Niedziela et al. "Selective Breakdown of Phonon Quasiparticles across Superionic Transition in CuCrSe2", Nature Physics, 15, 73-78 (2019). https://doi.org/10.1038/s41567-018-0298-2

[5] J. Ding et al. "Anharmonic lattice dynamics and superionic transition in AgCrSe2", PNAS 117 (8) 3930-3937 (2020). https://doi.org/10.1073/pnas.1913916117

[6] M. Gupta et al. "Fast Na diffusion and anharmonic phonon dynamics in superionic Na3PS4", Energy and Environmental Science (2021), https://doi.org/10.1039/D1EE01509E

Bio:

Olivier Delaire obtained his PhD in Materials Science from Caltech (2006). He joined Oak Ridge National Laboratory as a Clifford Shull Fellow in the Neutron Sciences Directorate (2008), later becoming Staff Researcher in the Materials Science and Technology Division (2012). In 2016, he became Associate Professor in the Thomas Lord Department of Mechanical Engineering and Materials Science at Duke University, with secondary appointments in the Physics and Chemistry departments. The Delaire group at Duke carries research at the interface of materials science, condensed matter physics and solid-state chemistry, with an emphasis on atomic dynamics. For instance, we investigate phonons in crystals and their interactions with electron or spin degrees-of-freedom, as well as ionic diffusion and phase transitions. 

Website: delaire.pratt.duke.edu 

 

*********************************** 10/20/2022 seminar ***********************************

Revealing the Structural Origins of Fracture Toughness in Bulk Metallic Glasses 

Prof. Jamie J. Kruzic

School of Mechanical and Manufacturing Engineering

University of New South Wales (UNSW Sydney), Australia

Thursday, October 20, 2022

4:00-4:50 pm Pacific Time

Abstract: 

Bulk metallic glasses (BMGs) are alloys with exceptionally high strength, and they can range from very tough to brittle depending on their structural state. However, quantifying their structure-property relationships has been an unresolved challenge because their amorphous glassy structures lack the long-range order and crystalline defects that typically define the structure-property relationships for crystalline alloys. In this work, we examine how local hardness variations within BMG microstructures strongly affect the fracture behavior and how the glassy microstructures can be altered by thermomechanical treatments such as cold deformation and cryogenic cycling to enhance the fracture toughness. Moreover, we have demonstrated using nanobeam electron diffraction and fluctuation electron microscopy that the hardness heterogeneities are controlled by the size and volume fraction of FCC-like medium-range order (MRO) clusters. Additionally, we have proposed a model of ductile phase softening whereby relatively soft FCC-like MRO clusters sit in a matrix of harder icosahedral dominated ordering, while micropillar compression testing has revealed how the activation of these clusters into shear transformation zones can be negatively affected by oxygen impurities which in turn lower the fracture toughness. Finally, the prospects for controlling the glassy structure and mechanical properties of BMGs using additive manufacturing by laser powder bed fusion will be discussed. 

Bio:

Jay Kruzic joined UNSW Sydney as a Professor of Mechanical and Manufacturing Engineering in 2016, and he was appointed Deputy Head of School in 2017. He was educated in the United States, receiving a B.S. degree in Materials Science and Engineering from the University of Illinois, Urbana-Champaign, in 1996 followed by M.S. and Ph.D. degrees in Materials Science and Mineral Engineering from the University of California, Berkeley, in 1998 and 2001, respectively. Following a period of three years as a postdoctoral fellow at Lawrence Berkeley National Laboratory he joined Oregon State University as an Assistant Professor in 2004. After being promoted to Associate Professor in 2008, he became Professor in 2014 in the School of Mechanical, Industrial, and Manufacturing Engineering at Oregon State University. His research focuses on the mechanical behaviour of a wide range of engineering materials (metals, ceramics, intermetallics, composites), biomaterials, and biological tissues, with emphasis on the mechanisms of fracture, fatigue, and deformation. 

 

*********************************** 10/27/2022 seminar ***********************************

Nucleation Reactions in Metallic Glass Alloys

Prof. John H. Perepezko 

Department of Materials Science and Engineering

University of Wisconsin-Madison 

1509 University Ave., Madison, WI 53706, USA, perepezk@engr.wisc.edu

Thursday, October 27, 2022

4:00-4:50 pm Pacific Time

Abstract: 

A growing number of metallic alloys have been discovered that can be synthesized as amorphous phases either during rapid melt quenching or by slow cooling of bulk volumes. In these systems crystallization reactions are effective in yielding nanoscale microstructures. For example, with amorphous Al alloys crystal densities can reach levels of 10^22 -10^23 m^-3. The crystallization kinetics determinations support a heterogeneous nucleation, but it is also evident that the kinetics are affected by transient effects. The initial nucleation appears to derive from quenched-in atomic arrangements to yield a high nucleation number density. The decaying growth rate at long time can be related to the impingement of diffusion fields from neighboring nanocrystals, but other factors may operate at short times.  Along with the advances in basic understanding of alloying to promote vitrification, there is a recognition that the structural models of amorphous alloys require refinements to account for local interactions and nanoscale heterogeneities that represent short range order as well as the development of medium range order. These are important issues that impact the analysis of the crystallization behavior during devitrification and the amorphous phase thermal stability. Beyond crystallization reactions, nucleation is critical for promoting useful ductility for structural applications of bulk metallic glasses. In this case, plastic deformation is concentrated in a narrow shear band that propagates rapidly. By promoting copious shear band nucleation throughout the volume of a bulk metallic glass, a more homogeneous deformation can be realized along with a useful ductility. The study and analysis of nucleation reactions for these different situations requires a consideration of the stochastic nature of nucleation and the influence of heterogeneous sites. These are new developments that offer exciting possibilities for control of nanoscale microstructures and deformation behavior as well as challenges for the fundamental understanding of the reaction mechanisms. 

Bio:

Professor John H. Perepezko is the IBM-Bascom Professor of Materials Science and Engineering at the University of Wisconsin-Madison. His honors and awards include the ASM Bradley Stoughton Award, Fellow of ASM , AGARD Visiting Lectureship, the Alexander von Humboldt Stiftung Forschungspreise, the TMS Bruce Chalmers Award, TMS Fellow, National Academy of Engineering, JSPS Fellow, TMS W. Hume-Rothery Award, MRS Fellow, Adjunct Professor -Tohoku University, Sendai, Japan and the Tokyo Institute of Technology and the Helmholtz Gemeinschaft International Fellow Award. He has served on several National Research Council committees and advisory panels for NASA, DOD and DOE. He is on the Editorial Board of Intermetallics. His research interests include transformation behavior and microstructure/property relationships during materials processing, metallic glass, intermetallic alloys, coatings, phase stability, modeling and materials design. He has authored over 475 publications and holds 15 patents. Professor Perepezko is a member of National Academy of Engineering. 

 

*********************************** 11/3/2022 seminar ***********************************

Where does the entropy of materials come from?

Prof. Brent Fultz 

Department of Applied Physics and Materials Science

California Institute of Technology (Caltech) 

Thursday, November 3, 2022

3:00-3:50 pm Pacific Time

Abstract: 

Entropy comes from atomic-scale degrees of freedom. For materials, most of the entropy comes from vibrations of atoms, and their vibrational amplitudes increase with temperature. The important question is usually how the entropy differs between different states of a material, such as a crystal with chemical order or chemical disorder. Historically, it has been a challenge to obtain these differences accurately by either experiment or theory. The methods are reliable today, and we use ab initio computation and inelastic neutron scattering to assess the entropies of materials over a wide range of temperatures. 

 

Entropy has its greatest thermodynamic importance at high temperatures, but here is where degrees of freedom become coupled. Normal modes of vibration are no longer independent, and interactions between vibrations and electrons also become important. I will describe how such couplings can be sorted out, and how they alter thermal expansion and other thermophysical properties of materials. Some of the behavior is surprising. 

Bio:

Prof. Brent Fultz is the Rawn Professor of Materials Science and Applied Physics at the California Institute of Technology. He received his B.Sc. from MIT, and his Ph.D. from U. C. Berkeley in 1982. After three years as a postdoctoral fellow and then a staff scientist at Lawrence Berkeley National Laboratory, Fultz joined the faculty at Caltech in 1985. As an assistant professor he was a Presidential Young Investigator, received an IBM Faculty Development Award, and a Jacob Wallenberg Scholarship. More recently, Fultz won the 2010 TMS EMPMD Distinguished Scientist Award, the 2016 William Hume-Rothery Award of TMS, and was elected Fellow of the Neutron Scattering Society of America in 2016, Fellow of the American Physical Society in 2017, and Fellow of TMS in 2018. He was named Outstanding Referee of Physical Review in 2019. Fultz has authored or co-authored approximately 400 publications, including graduate-level textbooks Transmission Electron Microscopy and Diffractometry of Materials (4th Ed with Jim Howe), and Phase Transitions in Materials (2nd Ed). 

 

*********************************** 11/10/2022 seminar ***********************************

Extreme Materials Processing for Clean Energy

Prof. Ju Li 

Department of Nuclear Science and Engineering

Department of Materials Science and Engineering

Massachusetts Institute of Technology (MIT) 

Thursday, November 10, 2022

4:00-4:50 pm Pacific Time

Abstract: 

To combat global climate change, the energy transition in the next decades is a civilization-scale endeavor, requiring tremendous minerals and new materials.  It must be "done right". Extremely fast joule heating, plasma exposure or photon and charged-particle radiations can be used to create materials unavailable with conventional synthesis methods. We have developed robotic workflows and active-learning-based automated approaches to search for appropriate processing parameters. This has led to new catalysts for water-splitting and CO2 reduction electrolyzers, as well as new liquid electrolyte and solid coating formulations for battery electrodes. The importance of rapid scaling-up to meet the climate challenges by 2040 is emphasized, taking grid-scale electricity storage as the example, where the techniques above can be applied to improve the safety and economy, as well as the recycling of "green wastes". 

Bio:

Ju Li has held faculty positions at the Ohio State University, the University of Pennsylvania, and is presently a chaired professor at MIT.  His group (http://Li.mit.edu) works on mechanical properties of materials, energy materials and systems. Ju is a recipient of the 2005 Presidential Early Career Award for Scientists and Engineers, the 2006 Materials Research Society Outstanding Young Investigator Award, and the TR35 award from Technological Review. Ju was elected Fellow of the American Physical Society in 2014, a Fellow of the Materials Research Society in 2017 and a Fellow of AAAS in 2020. Li is the chief organizer of MIT A+B Applied Energy Symposia that aim to develop solutions to global climate change challenges with "A-Action before 2040" and "B-Beyond 2040 technologies". 

 

*********************************** 11/17/2022 seminar ***********************************

Some Thoughts on Structure and Dynamics of High Temperature Metallic Liquids

and A Possible Relevance to Glass Formation

Prof. Ken Kelton 

Department of Physics

Institute of Materials Science and Engineering

Washington University in St. Louis 

Thursday, November 17, 2022

4:00-4:50 pm Pacific Time

Abstract: 

How to properly describe the structures of metallic liquids, whether structural changes in liquids correlate with changes in the dynamical properties, and what role this may play in glass formation and the glass transition remain outstanding questions.  Although it is widely believed that the dynamical behavior is linked to the atomic structure of the liquid, this has been difficult to demonstrate experimentally.  While the viscosity of the liquid changes by orders of magnitude with temperature, changes in the structure static structure factor, S(q), or pair correlation function, g(r), are almost negligible.   However, the recent development of containerless processing methods and the introduction of intense X-ray and neutron sources have enabled these changes to be accurately measured in deeply supercooled liquids.   This will be illustrated with select data from experimental studies.  Molecular dynamics (MD) and experimental studies of the viscosity in liquid metals have identified a crossover temperature near the liquidus temperature.  The MD studies suggest that this marks the onset of cooperative atomic behavior in shear flow.  Inelastic neutron scattering data are presented that support this.  Additional results are shown that confirm a general correlation between dynamics and structure in metallic liquids and point to a structural origin for liquid fragility. Fragility and the reduced glass transition temperature are widely believed to correlate with glass formability.  A way in which these quantities can be accurately estimated from properties of the high temperature liquid will be discussed. 

Bio:

Prof. Kelton is the Arthur Holly Compton Professor of Physics in Arts and Sciences at Washington University in St. Louis (WUSTL). He received his PhD and worked as a Postdoctoral Fellow at Harvard University prior to joining WUSTL. At WUSTL, he served as the Chair of the Physics Department 2007-2012 and became the inaugural Director of the Institute of Materials Science and Engineering in 2013. Prof. Kelton's Laboratory for Materials Physics Research studies the formation, structures, and physical properties of many materials, particularly novel non-crystalline phases of metals, such as quasicrystals, metallic and silicate glasses, and liquids. Prof. Kelton is an Elected Fellow of the American Physical Society, and Advisory Board member of Journal of Non-Crystalline Solids.