Available on-demand - *F.SF06.01.01
From High Entropy Alloys to Complex Concentrated Alloys—How to Tune Multiple Properties
Mathilde Laurent-Brocq1,D. Mereib1,T. Rieger1,Loic Perriere1,J. Monnier1,Y. Danard1,C. Vary1,H. Ben Kahla1,B. Villeroy1,Jean-Marc Joubert1,I. Guillot1,D. Mercier2,X.A. Wang2,P. Marcus2,M. Roussel3,A. Facco3
Université Paris Est Créteil, CNRS, ICMPE, UMR 71821,Chimie ParisTech, PSL University, CNRS, Institut de Recherche de Chimie Paris, Physical Chemistry of Surfaces Group2,Manoir Industries3
Since the discovery of the face-centered-cubic (fcc) single-phased CoCrFeMnNi and the proposal of the concept of high entropy alloys (HEA) in 2004, the understanding of the thermodynamic and mechanical behavior of those alloys has greatly increased. Indeed, it is now possible to reliably map the stable phases in the Co-Cr-Fe-Mn-Ni system using the CALPHAD method  and to calculate the solid-solution strengthening . So today, modelling tools are available to “investigate the unexplored central region of multi-component space” . It is time to go pass single-phase materials and/or equimolar quinary compositions and look for complex concentrated alloys. To do so, two different approaches will be presented.
First, the objective is to identify compositions of solid-solution to resist to severe environment (like high temperature and corrosive environment). The strategy consists in: (i) identifying criteria which are relevant for the targeted properties (like the yield strength, the Cr content or the cost) ; (ii) mapping those criteria for the entire composition space ; (iii) selecting compositions ; (iv) performing an experimental validation by processing, microstructural characterization and properties measurements. This will be presented for the Co-Cr-Fe-Mn-Ni and Co-Cr-Fe-Mo-Ni systems.
Second, the objective is to create a chemical architecturation within the CoCrFeMnNi alloy in order to strengthen it while preserving its ductility. More specifically, a mixture of pure Ni and CoCrFeMnNi powders is sintered in order to create chemical gradients at the interfaces of both phases . The microstructure of these innovative chemically architectured alloys will be characterized in detail. Then it will be shown how the width of the gradient can be controlled by varying the processing parameters and how it influences the mechanical properties. Finally, the different strengthening contributions will be sorted out and analyzed.
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