Synthesis and mechanical behavior of nanostructured high entropy alloy thin films by pulsed laser deposition - Archive ouverte HAL
Communication Dans Un Congrès Année : 2022

Synthesis and mechanical behavior of nanostructured high entropy alloy thin films by pulsed laser deposition

Résumé

High entropy alloy thin films (HEA-TFs) have become object of intense research in the last years due to the mutual combination of large strength and ductility, overcoming traditional bulk materials [1]. However, the field of thin film HEAs is still at its early stage and the effects of nanostructure on mechanical behavior have not been studied yet. In this context, pulsed laser deposition (PLD) offers the ability to control the morphology of the films by simply playing with the pressure during the deposition by adding an inert gas or by changing the laser wavelength and fluence (J/cm2) [2]. Here, we investigate the structure and mechanical properties of AlxCoCrCuFeNi thin films deposited by PLD investigating the effects of laser wavelength (1064 and 532 nm), deposition pressure (vacuum and 5 Pa He) as well as the Al content (from 0 up to 16 %at.). In addition, a second series of samples was grown by magnetron sputtering for comparison purposes. We show in Fig. 1 that CoCrCuNiFe films deposited in vacuum and at 5 Pa He are, respectively, compact and nanogranular. Moreover, we show that addition of Al (AlxCoCrCuFeNi) is responsible of a phase transition from FCC to BCC (at 16% at. Al), possessing a unique atomic structure alternating Alrich and CoCrCuNiFe nanolayers. The Young’s modulus and hardness of PLD films (175 and 10.8 GPa) are ~10% larger than magnetron sputtered films with a slightly decrement by addition of Al and for nanogranular film [3]. Tensile test on polymeric substrate (Kapton®) show that compact films have an outstanding onset of crack initiation up to ~3.5% which is higher vs literature (~2% [4]) and slightly decreasing by adding Al. The larger mechanical properties of PLD films can be related to the high energies of deposition and nanolayered structure. Overall, we show that PLD has the potential to synthetize a novel class of HEA-TFs with tunable mechanical properties and potential interest as structural coatings. References [1] Zou, Y. et al., Nat. Commun. 6, 2015. [2] M. Ghidelli et al., Acta Mater. 213, (2021). [3] Braeckman, B., Ghent University, (2016). [4] Li, C. et al., Surf. Coat. 402, (2020).
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Dates et versions

hal-04308639 , version 1 (27-11-2023)

Identifiants

  • HAL Id : hal-04308639 , version 1

Citer

Francesco Bignoli, Davide Vacirca, D. Faurie, P. Djemia, Fatiha Challali, et al.. Synthesis and mechanical behavior of nanostructured high entropy alloy thin films by pulsed laser deposition. Journées annuelles du GDR « Métallurgie des Alliages à Haute entropie ou à Composition Complexe », Sep 2022, Toulouse, France. ⟨hal-04308639⟩
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