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arXiv · 2102.05325

Nanocrystalline equiatomic CoCrFeNi alloy thin films: Are they single phase fcc?

Maya Kini·Subin Lee·Alan Savan·Benjamin Breitbach·Younes Addab·Wenjun Lu·Matteo Ghidelli·Alfred Ludwig·Nathalie Bozzolo·Christina Scheu·Dominique Chatain·Gerhard Dehm
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Abstract

The bulk quaternary equiatomic CoCrFeNi alloy is studied extensively in literature. Under experimental conditions, it shows a single-phase fcc structure and its physical and mechanical properties are similar to those of the quinary equiatomic CoCrFeMnNi alloy. Many studies in literature have focused on the mechanical properties of bulk nanocrystalline high entropy alloys or compositionally complex alloys, and their microstructure evolution upon annealing. The thin film processing route offers an excellent alternative to form nanocrystalline alloys. Due to the high nucleation rate and high density of defects in thin films synthesized by sputtering, the kinetics of microstructure evolution is often accelerated compared to those taking place in the bulk. Here, thin films are used to study the phase evolution in nanocrystalline CoCrFeNi deposited on Si/SiO 2 and c-sapphire substrates by magnetron cosputtering from elemental sources. The phases and microstructure of the films are discussed in comparison to the bulk alloy. The main conclusion is that second phases can form even at room temperature provided there are sufficient nucleation sites.

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Maya Kini, Subin Lee, Alan Savan, Benjamin Breitbach, Younes Addab, Wenjun Lu, Matteo Ghidelli, Alfred Ludwig, Nathalie Bozzolo, Christina Scheu, Dominique Chatain, Gerhard Dehm. 2021-02-10. Nanocrystalline equiatomic CoCrFeNi alloy thin films: Are they single phase fcc?. https://doi.org/10.1016/j.surfcoat.2021.126945

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