Structural characterisation of Cu-Zr thin film combinatorial libraries with synchrotron radiation at the limit of crystallinity. (June 2022)

• Record Type: Journal Article
• Authors: Putz, B.; Milkovič, O.; Mohanty, G.; Ipach, R.; Pethö, L.; Milkovičová, J.; Maeder, X.; Edwards, T.E.J.; Schweizer, P.; Coduri, M.; Saksl, K.; Michler, J.
• Is Part Of: Materials & design. Volume 218(2022)
• Publication Date: 2022-06
• Subjects: Combinatorial materials science -- Magnetron sputtering -- Thin film metallic glass -- X-ray diffraction -- TEM -- Structure analysis; Materials -- Periodicals; Engineering design -- Periodicals; Matériaux -- Périodiques; Conception technique -- Périodiques; Electronic journals; 620.11
• DOI: 10.1016/j.matdes.2022.110675
• Languages: English
• ISSNs: 0264-1275

Abstract

Graphical abstract: Highlights: Novel high throughput methodology to understand atomistic structure of thin film metallic glass combinatorial libraries on polymer substrates. Co-sputtered CuZr films exhibit dual-phase microstructure that could not be produced by conventional methods according to the CuZr phase diagram. Linear phase ratio between amorphous Cu51 Zr14 and nanocrystalline α-Zr as a function Zr content (25–80 at%), forming a mechanical mixture. Real space HR-STEM analyses of representative composition substantiate XRD results. Abstract: We report for the first-time combinatorial synthesis of thin film metallic glass libraries via magnetron co-sputtering at the limit of crystallinity. Special care was taken to prepare extremely pure CuZr films (1–2 µm thickness) with large compositional gradients (Cu18.2 Zr81.8 to Cu74.8 Zr25.2 ) on X-ray transparent polymer substrates in high-vacuum conditions. Combined mapping of atomic structure (synchrotron radiation) and chemical composition (X-ray fluorescence spectroscopy) revealed that over the entire composition range, covering multiple renowned glass formers, two phases are present in the film. Our high-resolution Synchrotron approach identified the two phases as: untextured amorphous Cu51 Zr14 (cluster size 1.3 nm) and textured, nanocrystalline α-Zr (grain size 1–5 nm). Real space HR-STEM analyses of a representative composition substantiate our XRD results. Determined cluster and grain sizes are below the resolution limit of conventional laboratory-scale X-ray diffractometers. The presented phase mixture is not permitted in the Cu-Zr phase diagram and contrary to existing literature. The phase ratio follows a linear trend with amorphous films on the Cu-rich side and increasing amounts of α-Zr with increasing Zr content. While cluster size and composition of the amorphous phase remain constant thorough the compositional gradient, crystallite size and texture of the nanocrystalline α-Zr change as a function of Zr content.