Centre for Engineering Materials (CEM)

Simulating materials for fusion and fission

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Wednesday, November 29th 2017
Sparck Jones Building SJ3/19
14:15 

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Abstract. Finding structural materials that can cope with the hostile environment of fusion and fission power plants is a famously difficult problem. In this talk I will describe work carried out over a number of years to understand some properties of defects in ferritic steels, and more recently in zirconium. Attention will be given to the computer models used, which are mostly quantum mechanical, and to the difficulties of capturing the important contribution made by magnetism and non-adiabatic effects.

Biography.  Andrew Horsfield joined the Materials Department at Imperial College in 2007 as an RCUK Fellow, is an honorary Research Fellow at the London Centre for Nanotechnology and a member of the Thomas Young Centre. His current research interests cover the dynamics of electrons out of equilibrium, and the thermodynamics of complex interfaces. Previous to this he was the Senior Research Fellow in charge of the theory core project for the IRC in Nanotechnology at UCL where he developed a novel scheme for non-adiabatic molecular dynamics (Correlated Electron-Ion Dynamics).

His interest in the interface between biology and physics was made possible by a Career Development Fellowship from the Institute of Physics which he received while working for the Fujitsu European Centre for Information Technology. His interest in efficient electronic structure methods and the development of two electronic structure codes (Plato and OXON) occurred while working in the Department of Materials at Oxford University with Prof. David Pettifor and Prof. Adrian Sutton. This built on his experience with tight binding while studying liquid silicon with Prof. Paulette Clancy at Cornell University as a PDRA and Junior Lecturer. He obtained his PhD in Physics from Cornell University.

All welcome to attend 

Enquiries to v.vishnyakov@hud.ac.uk

 

Porous ceramics and composites – from processing to simulation

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Wednesday, April 10th 2019
Sparck Jones Building SJG/11
11:15 

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Abstract. Cellular materials offer a wide spectrum of applications such as catalyst support structures, lightweight materials, energy adsorption or energy storage materials. Due to several ways of processing and different materials, a wide range of material properties e.g. thermal conductivity, mechanical strength or damping can be adjusted, measured and verified, with regard to the expected properties. Various techniques for processing porous ceramics and composites independent of material are presented. Especially in heterogeneous and homogeneous porous structures and their composites, only global effective material properties can be determined and measured. Knowledge on the predominating influence of the microstructure on the global properties is the key for designing materials with desired properties. To fill this gap and enable a "look-in" a model of microstructure derived from µCT measurements carried out at certain processing steps can be used as model for FEM-calculations. Combining estimated material properties by experiment with models of microstructure offers the possibility to carry out different simulations over different hierarchical levels. In contrast to experiments, also the pore network or the composite network and their influence on global parameters can be analysed. This approach is carried out on different cellular structures and composites (see Figure 1).

Figure 1: a) Pore network of a 30ppi replica foam, b) FEM-simulation of stress distribution in a MAX-phase gelcasted foam, and c) scaffold of hydroxyapatite building blocks and epoxy resin for block fixation. 

All welcome to attend 

Enquiries to v.vishnyakov@hud.ac.uk

 

Latest references:

Stumpf, M., Fan, X., Biggemann, J., Greil, P., Fey, T. Topological interlocking and damage mechanisms in periodic Ti₂AlC-Al building block composites, Journal of the European Ceramic Society (2019) 39(6), pp. 20032009, https://doi.org/10.1016/j.jeurceramsoc.2019.01.047

Biggemann, J., Pezoldt, M., Stumpf, M., Greil, P., Fey, T. Modular ceramic scaffolds for individual implants, Acta Biomaterialia 80 (2018) 390–400, https://doi.org/10.1016/j.actbio.2018.09.008

 Fey, T., Stumpf, M.,  Chmielarz, A., Colombo, P., Greil, P., Potoczek, M. Microstructure, thermal conductivity and simulation of elastic modulus of MAX-phase (Ti₂AlC) gel-cast foams , Journal of European Ceramic Society 38 (10)  (2018) 3424-3432, https://doi.org/10.1016/j.jeurceramsoc.2018.04.012

 Biggemann, J., Diepold, B., Pezoldt, M., Stumpf, M., Greil, P., Fey, T. Automated 3D assembly of periodic alumina-epoxy composite structures, Journal of American Ceramic Society 101 (10) (2018) 3864-3873 https://doi.org/10.1111/jace.15586        

 

Abstract

We have two visitors who will introduce us to their work at the Montanuniversitaet Leoben University (Austria).

Installation and capabilities of a high-end analytical scanning transmission electron microscope *Dr. Thomas M. Kremmer

*Chair for Nonferrous Metallurgy, Montanuniversitaet Leoben, Austria, thomas.kremmer@unileoben.ac.at

Understanding of material physics and its relation to the microstructure is necessary in order to improve the properties of advanced materials. Characterizing this relationship between the production, structure and final properties of materials can only be achieved via the use of the latest imaging and analytical techniques in combination with a high expertise in materials engineering. For this purpose a modern “Analytical Scanning Transmission Electron Microscope” was newly acquired from Thermofischer Scientific (Talos F200X).

This talk is dedicated to both the installation and capabilities of the new research infrastructure. In the first part, an overview of the installation and the necessary room adaptions to obtain excellent imaging conditions for TEM-work will be provided. This includes our setup for vibration dampening, air conditioning, electromagnetic field cancellation and common pitfalls in these areas during the planning stage. The second part focuses on obtained results in the areas of aluminium alloy development (especially precipitation of hardening phases) and radiation tolerant materials. Additionally, the possibilities for in-situ experiments (cooling, heating with MEMS-holder, 3d tomography) will be highlighted.

 

Phase Transitions in Quenched Metallic Systems Prof. Stefan Pogatscher*

*Distinguished Professor for Materials Engineering of Aluminum, Chair of Nonferrous Metallurgy, Montanuniversitaet Leoben, Austria, stefan.pogatscher@unileoben.ac.at

Nearly all classes of materials show non-equilibrium phase transitions and the first technological use of quenching metals for designing properties is documented as ~800 BC. However, the decomposition process towards equilibrium is still difficult to understand due to the strong non-equilibrium kinetics. Two examples are discussed: First the decomposition of a quenched super saturated solid solution and second the decomposition of a quenched metallic melt. In the first example the most frequently used group of precipitation hardened aluminum alloys – the AlMgSi alloys – is addressed. In these alloys natural aging affects the formability and the paint bake response for the use in automotive applications. Solute clustering upon natural aging, its implications on industrial aging treatments and the effect of trace elements are discussed. It is shown which physical pre-requisites need to be fulfilled to examine a “diffusion on demand” concept to modify clustering and precipitation kinetics by orders of magnitude. In the second example the discovery of the first solid–solid transition via melting in a metal, detected in the decomposition of a metallic glass, is demonstrated. The transformation path is discussed under its thermodynamic and kinetic prerequisites. Also the capabilities of the applied technique of fast scanning chip calorimetry are addressed. Finally, it is outlined how this novel method links the two examples via its potential for in-situ characterization of phase transitions upon rapid heating and cooling of small-scaled samples.