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Communication Dans Un Congrès Année : 2022

Novel nanostructured metallic thin films deposited by pulsed laser deposition with improved mechanical properties

Résumé

In recent years, thin metallic films have become increasingly important for several industrial applications due to the activation of mechanical size effects enabling a mutual combination of large yield strength and ductility1,2. However, the correlation between atomic/micro-structure and mechanical behavior is still not fully grasped and the research on new nanostructures with improved mechanical properties is still ongoing. In this context, pulsed laser deposition (PLD) offers vast and, so far, poorly exploited possibilities enabling an accurate control of the film morphology by simply playing with the deposition pressure. Specifically, films deposited in vacuum possess a compact morphology due to the atom-by-atom growth, while the addition of a background gas provide the formation of small atomic clusters, leading to a nanogranular morphology (cluster-assembled growth)3. In my project, I will show the potential of PLD for the synthesis and mechanical characterization of two classes of emerging metallic thin films, namely thin film metallic glasses (TFMGs) and complex compositional alloy (CCA) thin films. Firstly, I will cover the results involving the synthesis and the mechanical behavior of ZrCuAlx TFMGs with different compositions (x = 0,5,8,13 %at.) and morphologies (compact and nanogranular). I will show that our films are ~10% denser than literature counterparts (8.3 g/cm3 vs 7.4 g/cm3)4, while possessing a unique self-assembled nanolayered structure with local chemical enrichments, alternating ZrCu and Al rich nanolayers (Figure 1). This leads to a ~30% higher elastic modulus (E) and hardness (H) compared to sputter-deposited counterparts4 as well as to a larger onset of crack formation (~1.3%) when deformed in tension on polymeric substrates5. Micropillar compression tests show that compact ZrCu films have a brittle behavior due to the formation of shear bands while the nanogranular ones deform homogenously. In the second part of the talk, I will present preliminary results focusing on AlxCoCrCuFeNi CCA thin films deposited by PLD with different compositions (x = 0,9,16 %at.) and morphologies, i.e., compact and nanogranular. Films possess an FCC nanocrystalline structure with tunable crystallite size which can be controlled by the deposition parameters and leading to enhanced E and H vs sputter-deposited counterparts6. In addition, our films report an exceptionally high (>3.5%) onset of crack formation when deformed on polymer substrate as a result of high energy of the deposition process, leading to strong adhesion and preventing crack formation. Overall, the presented results show the potential of PLD to synthetize a novel class of metallic thin films with tunable mechanical properties and large interest as structural coatings. References [1] J. P. Chu et al., Thin Solid Films, 16, 2012; [2] Y. Zou et al., Nat. Commun., 6, 2015; [3] M. Ghidelli et al,, Acta Mater., 213, 2021; [4] P. Yu et al., Mater. Sci. Eng. a, 45, 2008; [5] A. Brognara et al., Mater. Des., 219, 2022; [6] B. Braeckman et al., Surf. Coat., 315, 2017. Figure 1: HRTEM (a) and STEM (b) images of a compact ZrCuAl8 film highlighting the Al-rich layers (in yellow).
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hal-04308827 , version 1 (27-11-2023)

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  • HAL Id : hal-04308827 , version 1

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Francesco Bignoli, D. Faurie, P. Djemia, Andrea Li Bassi, Matteo Ghidelli. Novel nanostructured metallic thin films deposited by pulsed laser deposition with improved mechanical properties. Seminar of PhD students at LSPM, Nov 2022, Villetaneuse (Université Paris 13), France. ⟨hal-04308827⟩
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