Thematic research areas
Neo-metallurgy: New alloys, new processes and new investigation techniques
The focus of this thematic area is the development of new alloys and processing routes for various applications, and the improvement of characterisation techniques.
Efficient development of new metallic alloys for structural or functional applications relies on the possibility of making combinatory experiments in a fast and efficient way. One way is to produce materials with composition gradients, with testing made afterwards at a very local scale (e.g. nano-indentation for mechanical properties, or local optical/ electrical measurements for functional properties). However, the question arises on the feasibility of up-scaling properties measured at a very local scale to properties of more bulk materials. This up-scaling will often lead to fundamental questions when the characteristic length scales associated with the phenomena involved become comparable to that of the specimen or of the measurement technique.
In order to industrially produce these new alloys, new processing routes are required. For example, new materials such as bulk metallic glasses, metallic foams, and metal matrix composites offers new and quite unique mechanical properties yet are difficult to fabricate in bulk. Laser welding of dissimilar materials is also of great interest for many industries from the watch or medical sectors to the automotive and aeronautic sectors. While the metallurgy of the base elements within an alloy may be well known, the combination of elements by metallurgical bonds requires a deep understanding of both thermodynamics and processing.
Finally, novel characterising techniques such as in situ X-ray radiography or tomography, neutron scattering, orientation imaging using EBSD combined with chemical analyses, nano-testing devices, etc., allow one to characterise accurately and in depth metallic alloys down to very low scale. While some of these techniques are relatively mature, others still require considerable effort to achieve a single result. In all cases, improvements in speed, accuracy, and resolution of these techniques will aid in developing new alloys and new processing routes.
On-going projects in this thematic research area:
- Evolution of microstructure and mechanical response due to cyclic deformation at elevated temperatures
- In-situ mechanical testing
Multi-scale, multi-phenomena modelling of metallic systems
At the same time as new alloys are being produced and experimentally analysed, computer simulation has really become an indispensable tool in metallurgy. For traditional metallurgy of standard composition alloys, the effort of researchers is directed towards integrated modelling in order to model, understand, calculate and optimise processing routes as a function of the final desired properties. The newest form of modeling is known as multi-scale modeling, in which many different effects, from the atomistic scale to the process scale, are linked. This type of modeling requires the development of dedicated tools which can encompass nearly ten orders of magnitude.
Modeling metallic systems can take many forms. At the scale of a small population of atoms, ab initio calculations can be used to model the optical or electrical response of metallic systems. At the scale of a few million atoms, molecular dynamics can help in the understanding and calculation of mechanical properties of nanoparticles, the structure and property of diffuse solid-liquid interfaces or the interactions between metallic systems and radiation. Numerical simulation methods such as pseudo-front tracking and phase field methods are used to model the formation of microstructure and defects in multi-component and multiphase systems. At larger scales, granular approaches or cellular automata can be used to model interactions of macrostructures, i.e. at the scale of a large population of grains, while still incorporating grain boundary interaction. Finally, models can be developed using, for example, finite elements or computational fluid dynamics, to simulate entire industrial processes at the macro scale.