Atomistic Design of Multi-Component Metal Alloys and Glasses

Colloq: Speaker: 
David Riegner and Wolfgang Windl
Colloq: Speaker Institution: 
The Ohio State University
Colloq: Date and Time: 
Wed, 2016-11-09 10:00
Colloq: Location: 
Building 5700, Room MS-A106
Colloq: Host: 
Philip Roth
Colloq: Host Email: 
rothpc@ornl.gov
Colloq: Abstract: 
DOE-EM is responsible for liquid, glass, ceramic, and metallic nuclear waste that must be safely isolated from the environment for long periods. This requires understanding both the performance and fundamental mechanisms of waste form degradation and the design of new waste forms with improved performance. These tasks comprise the goals of WastePD, a new EFRC at The Ohio State University. Within its project portfolio, WastePD targets designing novel metal alloys with improved corrosion resistance, with focus on multi-component systems, specifically high-entropy alloys (HEAs) and bulk metallic glasses (BMGs), which promise to have outstanding mechanical properties and corrosion resistance. While traditional alloys are primarily based on one or two components, both HEAs and BMGs frequently contain five or more components in comparable concentrations. The high concentrations of many metallic components make it challenging to find alloys that form single-phase HEAs or BMGs that are able to vitrify into amorphous structures. In this talk, we will discuss work and computational challenges centered on identifying sets of elements capable of being combined successfully into new crystalline or amorphous alloys. Our work is partially based on classical-potential molecular dynamics simulations, for which the first challenge is to develop analytical or numeric functions (“empirical potentials”) that describe the interatomic energies and forces in a multicomponent system sufficiently well. These functions are then used to study vitrification/crystallization of metallic liquids by molecular dynamics (MD) simulations, which involve lengthy computations for large numbers of atoms. Here, we will describe the challenges and approaches for developing the interatomic potentials, as well as performing and analyzing the MD runs. As an alternative, we will also describe a novel multi-cell Monte Carlo approach that allows studying phase decomposition (i.e. demixing of the alloy) with high computational efficiency that enables the use of high-accuracy quantum-mechanical methods to describe the interatomic forces instead of the empirical potentials.
Colloq: Speaker Bio: 
Wolfgang Windl is a Professor in the Department of Materials Science and Engineering at The Ohio State University and works in the area of Computational Materials Science. Before joining OSU in 2001, he spent four years with Motorola, ending his tenure as Principal Staff Scientist in the Digital DNA Laboratories in Austin, TX, where he was working in the area of multiscale modeling of semiconductor processing. Previously, he held postdoctoral positions at Los Alamos National Laboratory with Art Voter and Arizona State University with Otto Sankey. He received his diploma and doctoral degree in physics from the University Regensburg, advised by Dieter Strauch. Among others, he received the first Fraunhofer-Bessel Research Award from the Humboldt Society in 2006; a 2004 Nanotechnology Industrial Impact Award from the Nano Science and Technology Institute; 1998 and 1999 Patent and Licensing Awards from Los Alamos National Laboratory; three Lumley Research Awards and one Ralph-Boyer Teaching Award from the College of Engineering at The Ohio State University; and 2006 and 2015 Mars Fontana Best Teacher Awards of the Department of Materials Science and Engineering at the Ohio State University. David Riegner is a Postdoc within WastePD at The Ohio State University and works in the area of Computational Materials Science. He received his PhD in Materials Science from OSU in 2016 and received during his graduate time several awards and recognitions, including a best-poster award at the OSU Hayes Graduate Research Forum and the inaugural Woolley Teaching Fellowship within the MSE Department.