F. Tancret, I. Braems, E. Bertrand, L. Couturier

Our team, a pioneer in France in the domain, develops computer-aided alloy design methods, associating physical models (including computational thermodynamics using Calphad method and ab initio simulation) with artificial intelligence tools like data mining (machine learning) and multi-objective optimisation by genetic algorithms. These works, undertaken within academic or industrial collaborations, deal with many categories of materials (alloys based on Fe, Ni, Ti, Al, Mg; high entropy alloys HEA; complex concentrated alloys / compositionally complex alloys CCA), for a variety of applications (oil & gas / petrochemistry; energy / nuclear domain; aeronautics, automobile; micromechanics…).

Keywords: Alloy design, neural networks, first principles, Thermo-Calc, steels, stainles

F. Tancret, E. Bertrand

This is our most ancient activity (started in 1998), which was the frame of the development of a large part of our skills on computational alloy design (data mining / machine learning, physical models including computational thermodynamics, multi-objective optimisation by genetic algorithm…), and that led to numerous pioneering papers in the domain and to the most integrated method to date. Examples of achievements are presented below.

 Keywords: Neural networks, Gaussian processes, Calphad, Thermo-Calc, weldable

F. Tancret

Postdoc of Edern Menou (2017-2018). Industrial collaboration with Safran, on the design of new single-crystal superalloys for turbine blades. Improvement of the specific creep strength and of the high temperature oxidation resistance.

Filing of two patents:

J. Rame, E. Menou, C. Desgranges, F. Tancret – Low density nickel-based superalloy having high mechanical strength and environmental robustness at a high temperature – FR3091708 / WO2020148503

J. Rame, E. Menou, C. Desgranges, F. Tancret – Nickel-based superalloy having high mechanical strength at high temperature – FR3091709 / WO2020148504

F. Tancret, I. Braems, L. Couturier, E. Bertrand

This research, initiated as a collaboration with the University of Cambridge, are undertaken within the frame of ANR project Cadohrs (Computer-Aided Design of Hydrogen-Resistant Superalloys), notably through the PhD studentship of Aman Prasad (2020-2023) and the postdoc of Ranim Mohamad (2020-2021). It aims at designing nickel alloys that are resistant to hydrogen embrittlement, via an understanding, through the study of model alloys and ab initio simulation, of the influence of composition on the embrittlement of the matrix and on hydrogen trapping by precipitates.

Keywords: Superalloys, corrosion, strength, nuclear, oil & gas

F. Tancret, E. Bertrand

High Entropy Alloys (HEA) constitute a new class of metallic materials, studied since 2004. They consist in mixtures of at least five elements, all with contents between 5 and 35 at.%, forming a single solid solution. Whereas most HEAs had been discovered fortuitously, though trial-and-error or in a rather empirical manner, we have undertaken the project, as a collaboration with the University of Cambridge and during the PhD studentship of Edern Menou (2016), of designing HEAs by combinatorial optimisation relying on modelling and machine learning. After experimental validation we have obtained alloys whose properties surpass those of HEAs having the same structure and microstructure, and sometimes even those of other categories of alloys. Among others, the highest substitutional solid solution hardening ever reported was achieved.

Keywords: Multi-element alloys, multi-principal element alloys, complex concentrated alloys, compositionally complex alloys

F. Tancret, E. Bertrand, L. Couturier

The definition of Complex Concentrated Alloys, or Compositionally Complex Alloys (CCA), is not very precise. One could define them as “baseless”, “multi-concentrated” or “multi-principal” alloys (MPEA), similarly to HEAs but that, contrarily to the latter, would develop polyphaser microstructures, may it be in the as-solidified state, following a precipitation heat treatment or during deformation (“TRIP” effect). It would then be an extension of the concept of HEA towards more classical metallurgies like those of steels or superalloys. As in the case of HEAs, original combinations of properties are looked for, that could potentially be exploited for certain applications. Here are presented various projects in which we are working on the computational design of CCAs.

 Keywords: Hgh entropy Alloys, multi-element alloys, high entropy superalloys

F. Tancret

Whereas classical alloys are often associated to certain processes (casting, forging, powder metallurgy…), the beginnings of additive manufacturing have above all seen its application to existing grades, poorly adapted to these new processes. Our works deal with the design of alloys (stainless steels, alloys of nickel or titanium, high entropy alloys…) specifically adapted to additive manufacturing, may it be to reduce defects and improve quality (cracking, porosity, surface aspect…), to optimise mechanical properties, or to deposit layered multi-materials with original characteristics (notably a high resistance to crack propagation).

 Keywords: ALM, SLM, DMD, multilayer materials

F. Tancret

We are developing a method to design alloys with a composition allowing to minimise their environmental impact (water usage, carbon footprint, embodied energy / energy, pollution of soils…) and their criticality (geological and geopolitical availability, volatility of prices on markets), to maximise their ability to be recycled and the possibility to produce them from recycled alloys, while maintaining good mechanical properties.

 Keywords: eco-design, geo-design, eco-materials