Our students and researchers in the spotlight! SF2M rewards three colleagues in 2020.

Among the twelve SF2M winners of the year 2020 are Daniel Pino Muñoz, Alexis Nicolaÿ and Artur Alvarenga. CEMEF's metallurgy activity is honoured and rewarded.

Congratulations to our three winners: Daniel Pino Muñoz, Alexis Nicolaÿ and Artur Alvarenga. The award ceremonies should normally take place during the annual SF2M days. The ceremony finally took place virtually on 17 December 2020. This does not take anything away from the talents of our recipients!

Daniel Pino Muñoz is a researcher in the CSM team. He is the recipient of the Jean Rist 2020 Medal. His research work focuses on the development of numerical tools to simulate microstructural evolutions in crystalline materials.

Brayan Murgas is at the origin of this magnificent composition made from images from his work.

Congratulation Brayan Murgas! This image is both scientifically meaningful and aesthetically very successful. No wonder it caught the public's interest when it was awarded the "Arts & Science Contest" prize at the WCCM Ecomas International Conference held online last week.

Brayan Murgas is a 3rd year doctoral student in the MSR team. He is working on a fine description of the mobility of grain joints for its numerical integration in finite element simulations of recrystallisation mechanisms.

The origin of this image began when I started his PhD at CEMEF.

Brayan received his laptop and was looking for a wallpaper. He came up with the idea to do it by himself with the images he obtained from his first simulations. 

To improve the Finite Elements modes, he uses Scanning Electron Microscopes allowing to properly describe grain boundaries.

The images used here represent the steps to immerse EBSD data into a Finite Element code: the Band contrast map which is an EBSD pattern that describes the average intensity of the Kikuchi bands.

The kikuchi bands are formed by electron scattering and describes the orientation of every pixel which is represented in the form of an inverse pole figure in the second slice of the image.

Finally he uses the orientation data of every pixel to construct the three last slices of the image: distance, orientation and grain boundary mobility fields.

With this methodology he can directly compare his results to experimental data and also he replaces in-situ experiments which are time consuming and difficult to perform.

Ayoub Aalilija defends his PhD in Numerical Mechanics and Materials on Dec. 21, 2020.

Numerical modelling of chill cooling of levitated steel melts solidified in the International Space Station

Ayoub Aalilija conducted his PhD work in  2MS team, under the supervision of Charles-André Gandin in the framework of ESA, the European Space Agency. He defends his PhD in Numerical Mechanics and Materials on Dec. 21, 2020 in front of the following juy:

Abstract:

The study of solidification in microgravity allows researchers to dissociate gravity-independent phenomena from gravity-dependent ones. The objective is to reach a better understanding of solidification allowing the metallurgical industry to meet the expected properties of their metal products and to avoid the defects that appear during their elaboration. In this context, the NEQUISOL and CCEMLCC projects of the European Space Agency are taking place. As part of these two projects, we propose a numerical framework to simulate the solidification experiments of metallic samples in electromagnetic levitation in the International Space Station. Our numerical tool is based on the finite element resolution of the conservation equations of energy, total mass, momentum and mass of the chemical species of a multi-domain system involving a multicomponent metal alloy. A monolithic formulation allows the resolution of one set of equations on a single Eulerian mesh. A stabilised VMS Finite Elements formulation is proposed to solve the Navier-Stokes equations. The modelling is enriched by taking into account solidification shrinkage, surface tension and the Marangoni effect acting at the liquid-gas interface. A contact thermal resistance model is developed and validated enabling the consideration of thermal contact imperfections between the different materials. The Level Set method is used to model the interfaces between the sub-domains. The liquid-solid interface within the metal sub-domain is implicitly represented by the volume average methodology. In a first step, we propose simulations of measurement experiments of surface tension and viscosity of liquid metals using the oscillating drop technique in microgravity. This benchmark offers a quantitative comparison between the numerical results and an analytical solution that we derived in both 2D and 3D.  Once we have validated our numerical modelling of the dynamics of the liquid-gas interface, we perform simulations of the solidification of a steel droplet and compare it with data from the first and unique experiment performed on board the International Space Station in the framework of the CCEMLCC project.

 

 

 

Keywords: Numerical simulation; Finite Element; Level Set; Surface tension; Marangoni; Thermal contact resistance; Oscillating drop; Solidification; Microgravity

 

Vincent Maguin defends his PhD in Numerical Mechanics and Materials on Nov. 16th, 2020.

"Multiphysic model of macrosegregation and development of freckles during solidification of single crystal turbine blades"