Poster De Conférence Année : 2025

Refractory high entropy alloy thin films with controlled oxygen addition

Résumé

Developing new materials with high strength and ductility that can withstand harsh environments remains a key challenge for microelectromechanical systems (MEMS) and energy storage applications. Refractory high entropy alloys (RHEAs) with a BCC structure can represent promising materials for these industrial applications due to their high strength, oxidation, and corrosion resistance [1]. However, these alloys often exhibit low ductility at room temperature [2]. To overcome this drawback, one approach consists of adding ductile FCC elements to the BCC phase to promote the formation of a dual-phase (BCC-HCP) structure, balancing strength-ductility [3]. Another strategy is the addition of small amounts of nonmetallic elements, particularly oxygen, which form ordered oxygen complexes that act as dislocation pinning points and help mitigate brittle behavior [4]. However, most of these studies focus on bulk RHEAs, while there are limited studies on thin film counterparts (RHEA-TFs, thickness < 1µm), especially their relationship between microstructure and mechanical properties. Firstly, I will present some preliminary results on Fex(CoCrNi)100-x HEA-TFs deposited by magnetron sputtering, with Fe content varying from 13 to 29 at.%. CoCrNi showed a dual FCC-HCP phase, contributing to a hardness of 9.7 GPa and an elastic modulus of 204.4 GPa, while the FCC phase was stabilized with Fe addition. Then, I will present the core research of my PhD thesis, focusing on the deposition of TiZrHf RHEA-TFs via magnetron sputtering with a progressive addition of Al (up to 25 at.%) and O (up to 15 at.%), to investigate film growth mechanisms, atomic structure evolution, and microscale mechanical properties using a scale-bridging approach from the nm up to the µm scale. [1] C.H. Chang et al., Adv. Eng. Mater., 8,2018; [2] O. N. Senkov et al., Intermetallics, 19, 2011; [3] L. Rogal et al., Sci. Rep., 7, 2017; [4] Z. Lei et al., Nature, 563, 2018.

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Dates et versions

hal-05030496 , version 1 (11-04-2025)

Identifiants

  • HAL Id : hal-05030496 , version 1

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Ayadjenou Humphrey Hounsinou, Arjun Bharath Curam, Jaysen Nelayah, Matteo Ghidelli. Refractory high entropy alloy thin films with controlled oxygen addition. Journées annuelles 2025 du GDR HEA, Apr 2025, Villeurbanne (France), France. 2025. ⟨hal-05030496⟩
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