25 اسفند

Title: "Microstructure selection during solidification processes from multiscale modeling approaches"
Presenter: Dr. Damien Tourret
- Affiliation: IMDEA Materials Institute, Madrid, Spain
- Position: Researcher and the leader of the research group on Modeling and Simulation of Materials Processing
Date: Wednesday, March 16 (Esfand 25), 17:30
Address: https://vc.sharif.edu/ch/mse-webinar

:Abstract
The processing of a material controls the development of its microstructure, and the formation of defects that ultimately dictate its properties and performance. In structural materials such as metallic alloys, microstructures typically emerge during the stage of solidification from the liquid phase. As such, understanding the development of microstructural features during solidification is key to advance the development of new materials and processes to produce novel microstructures and outstanding properties. From a fundamental standpoint, complex solidification microstructures, such as dendrites, arise from a subtle interplay between phenomena across a broad range of scales – from atomic attachment kinetics to macroscopic transport of heat and species in the different phases. As such, solidification modeling contains major scale-bridging challenges, and the fundamental understanding of solidification still holds long-standing unknowns related to mechanisms of intra- and inter-grain dendritic microstructure selection, or the origin of some morphological transitions in metallic microstructures.
This talk will focus on theory, modeling, and simulation of dendritic growth at scales ranging from a single dendrite (~ micrometer) to a grain structure (~ centimeter). I will highlight two specific examples of how computational modeling has brought a deeper understanding of nontrivial mechanisms of microstructure selection during dendritic solidification. The first example revolves around grain boundary selection during dendritic grain growth competition in polycrystalline materials, which was adressed using quantitative phase-field modeling [1,2]. The second example focuses on the effect of buoyant fluid flow during directional solidification, and resulting oscillatory instabilites that were recently observed using in situ x-ray imaging on Nickel-based superalloy CMSX4 [3] and which we recently explained using a multiscale dendritic needle network model approach [4,5]. Both of these examples have brought new insight that is relevant, for instance, to the growth of single crystal components, such as those used in the directional casting of aeronautical turbine blades.
[1] D. Tourret, A. Karma, Acta Materialia 82, 64-83 (2015)
[2] D. Tourret, et al., Acta Materialia 122, 220-235 (2017)
[3] G. Reinhart, et al. Acta Materialia, 194, 68-79 (2020)
[4] D. Tourret, A. Karma, Acta Materialia 120, 240-254 (2016)
[5] D. Tourret, et al., Computational Materials Science 162, 206-227 (2019)

:Short bio
Damien Tourret is a staff researcher at IMDEA Materials Institute in Madrid (Spain), a Ramon y Cajal fellow, and the leader of the research group on Modeling and Simulation of Materials Processing.
Damien Tourret received a MSc in Mechanical Engineering from INSA Toulouse (France) in 2006 and a PhD in Materials Science & Engineering from Ecole des Mines de Paris (France) in 2009. Before joining IMDEA Materials in 2017, Damien was a Director's Postdoctoral Fellow at Los Alamos National Laboratory (Los Alamos, NM, USA) from 2014 to 2017. He also held postdoctoral positions at the German Aerospace Center (DLR, Cologne, Germany) from 2010 to 2011, and at Northeastern University (Boston, MA, USA) from 2011 to 2014.
His main research interests revolve around linking materials processing routes to microstructures and properties, with a particular emphasis on multi-scale modeling of solidification and phase transformations in metallurgical processing of metals and alloys