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After participating in this webinar series, attendees will understand the ways that entropy is different in a variety of materials. Attendees will also gain an improved understanding of thermodynamics as they apply to high entropy alloys and complex, concentrated alloys.
If you can’t attend the live events, don’t worry—recordings for both webinars are included in the registration fee. TMS members have free access to both the live and recorded events, but still need to register to participate.
Webinar 1: Hume-Rothery Award Talk: The Origin of Entropy in Materials
Date: Thursday, December 15 • 1:00 p.m. to 2:00 p.m. (EST)
Instructor: Brent Fultz, Professor, California Institute of Technology
Most of the entropy of materials comes from vibrations of atoms—vibrational entropy is typically an order-of-magnitude larger than other sources, such as configurational entropy. Historically, differences in vibrational entropy between different phases have been subtle and troublesome to assess. Some trends and rules emerged over the years, such as how the formation of short, stiff bonds tends to reduce the vibrational entropy. The situation at high temperatures is complicated, but arguable more important for materials processing. At elevated temperatures, the harmonic and quasiharmonic approximations are unreliable. All materials have phonon-phonon interactions at high temperatures because interatomic potentials are not perfectly harmonic. Metals also have electron-phonon interactions, and magnon-phonon interactions are important for iron, for example. For less-complicated materials, it is exciting that we can now measure or calculate accurately the different parts of entropy at elevated temperatures, even when the material is far from a harmonic solid.
For the most part, materials science textbooks do not address the origin of entropy, merely that it exists. There are some rules of thumb that suggest how entropy and free energy can be controlled, but precise numbers require real work. Over the next generation, calculations could replace heat capacity measurements for determining thermodynamic quantities. However, this requires that all pieces of the free energy are accurate.
- What entropy is, and how it dominates thermodynamics at temperature
- What are the sources of entropy and how big are they?
- How do we calculate or measure the pieces of entropy?
- Example of body-centered cubic (BCC) iron
- Example of rutile TiO2
- Example of FeTi
- What is a material?
The Hume-Rothery Award Talk: The Origin of Entropy in Materials webinar is sponsored by the TMS Functional Materials Division.
Webinar 2: Thermodynamics of High Entropy Alloys and Related Concepts
Date: Tuesday, December 20 • 1:00 p.m. to 2:00 p.m. (EST)
Instructor: Daniel B. Miracle, Senior Scientist, Materials and Manufacturing Directorate, Air Force Research Laboratory
High entropy alloys (HEAs) contain five or more elements with atomic concentrations between five and 35%. The concepts of entropy and enthalpy are central to HEA studies, but consideration of thermodynamic quantities is usually limited to ideal cases and other simplifications. Here we consider classical thermodynamic concepts as they apply to HEAs and complex, concentrated alloys (CCAs). We discuss the entropy and enthalpy of mixing for solid solutions, and formation of entropies and enthalpies of intermetallic compounds. We also discuss the relative magnitudes of excess entropy terms, the effects of high concentrations of different-sized atoms, Gibbs phase rule, and the importance of achieving equilibrium in HEAs and CCAs. We evaluate the hypothesis that high configurational entropy may influence the formation of disordered solid solution phases. We show that configurational entropies of metallic solutions are rarely ideal, and we introduce other “surprises” in thermodynamics of HEAs and CCAs.
Attendees of this webinar will gain an improved understanding of thermodynamics as they apply to HEAs and CCAs. The information presented during this webinar can be readily applied to better design scientific studies of HEAs and CCAs, and to more accurately interpret published data and results.
- Introduction and definitions
- Entropy and enthalpy of disordered solid solution (SS) phases
- Entropy and enthalpy of intermetallic (IM) phases
- Systems with different atom sizes
- Relative magnitudes of excess entropy terms
- Comparing Gibbs energies of competing phases
- Gibbs phase rule
- Assessing the high entropy hypothesis
- Summary and concluding remarks
The Thermodynamics of High Entropy Alloys and Related Concepts webinar is sponsored by the TMS Structural Materials Division (SMD), and the following committees of the SMD:
- Advanced Characterization, Testing & Simulation Committee
- Alloy Phases Committee
- Chemistry and Physics of Materials Committee
- Corrosion and Environmental Effect Committee
- High Temperature Alloys Committee
- Mechanical Behavior of Alloys Committee
- Refractory Metals and Materials Committee
Meet the Instructors
Brent Fultz , professor at California Institute of Technology, received his undergraduate degree from Massachusetts Institute of Technology and his Ph.D. from the University of California, Berkeley. He was a Presidential Young Investigator, and more recently was awarded the 2010 TMS Electronic, Magnetic & Photonic Materials Division (now Functional Materials Division) Distinguished Scientist Award and the 2016 William Hume-Rothery Award. He serves on review boards of the Advanced Photon Source and the National Institute of Science and Technology Center for Neutron Research, and was elected a Fellow of the Neutron Scattering Society of America in 2016. Fultz has authored or co-authored nearly 400 publications, including the textbook with J.M. Howe on Transmission Electron Microscopy and Diffractometry of Materials, now in its fourth edition, and the new graduate-level textbook Phase Transitions in Materials (Cambridge, 2014).
The main topic of Fultz’s research is how the entropy and free energy of materials originate at the level of atoms and electrons. Vibrations are the main source of entropy of solid materials. They are quantized as “phonons,” which are measured by inelastic neutron scattering. Inelastic neutron scattering can also measure magnetic and electronic excitations, and these excitations can have thermodynamic importance, too. Most of scientific challenge is identifying the reasons for differences in phonon entropy of different materials, and how the phonon entropy changes with temperature and pressure. Recent work has focused on behavior over a broad range of temperature, where phonons interact with other phonons, and with electronic excitations. Fultz’s group has also been measuring how vibrational thermodynamics is altered in materials under high pressures, as in diamond anvil cells.
Daniel B. Miracle is a senior scientist in the Materials and Manufacturing Directorate of the Air Force Research Laboratory (AFRL), where he shares responsibility for the quality, balance, and focus of the technical program and the quality and balance of the technical workforce. He represents technologies of interest to the U.S. Air Force and leads formation of technical partnerships through interactions with universities, industry, and the international scientific community. As a senior technical leader, Miracle represents the Department of Defense in the formation of major technical alliances with other governments. He is a member of the AFRL Research Council, which is responsible for defining strategies, policies, and workforce development for a staff of over 3,400 scientists and engineers.
Current research interests include basic studies of amorphous metals and development of complex, concentrated alloys for structural applications. Miracle received his B.S. in materials science and engineering from Wright State University, his M.S. and Ph.D. in metallurgical engineering from The Ohio State University, and an Honorary Doctor of Science from the Institute of Metal Physics, Ukrainian Academy of Sciences, Ukraine. Miracle is a Fellow of ASM International and a Fellow of the AFRL. Dr. Miracle has received the Air Force Basic Research Award, the Air Force Scientific Achievement Award, and was co-recipient of the Department of Energy Outstanding Scientific Accomplishment award. He is author or co-author of more than 190 peer-reviewed scientific articles and six book chapters, and is co-editor of six books. He is co-inventor on eight patents and has given more than 150 plenary, keynote, and invited talks at national and international scientific venues in 18 countries.
The live webinars in this series were held in December 2016, but the recordings are still available for purchase.
This webinar series is a free event for TMS members**. Members will still need to complete the registration process in order to access live or recorded webinar links. Registration fees will give you access to both webinars in the series. Upon registering, event details and links will be provided in a separate e-mail. To ensure delivery of your webinar link in time for the live events, please register 24 hours prior to the start time.
(Live event or recorded event)
* Must be a full-time undergraduate or graduate student to receive the student rate; a copy of student school identification card is required; must e-mail a copy of ID card to TMS Meeting Services
** The free TMS member registration rate applies to all individual (including retired and lifetime) members, recent graduates, and Material Advantage students. International e-members, affiliate members (ABM and IOM3), and non-Material Advantage students do not qualify for the free TMS member rate. For more information on different types of TMS membership and benefits, view the TMS Membership Benefits Chart.
CANCELLATION/REFUND POLICY: TMS reserves the right to cancel this webinar due to low registration; registrants will be notified at least 24 hours prior to the start of the live event and will receive a full refund. If a registrant must cancel, TMS must be notified in writing (by e-mail or mail) before December 8, 2016; payment will be refunded less a $20 processing fee. No refunds will be processed after December 8, 2016.
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