In-situ TEM investigation of microstructural evolution in magnetron sputtered Al–Zr and Al–Zr–Si coatings during heat treatment. (5th January 2016)

• Record Type: Journal Article
• Authors: Gudla, Visweswara Chakravarthy; Rechendorff, Kristian; Balogh, Zoltan Imre; Kasama, Takeshi; Ambat, Rajan
• Is Part Of: Materials & design. Volume 89(2016)
• Page Start: 1071
• Page End: 1078
• Publication Date: 2016-01-05
• Subjects: In-situ TEM -- Heating -- Magnetron sputtering -- Al–Zr -- XRD -- Microstructural evolution; Materials -- Periodicals; Engineering design -- Periodicals; Matériaux -- Périodiques; Conception technique -- Périodiques; Electronic journals; 620.11
• DOI: 10.1016/j.matdes.2015.10.081
• Languages: English
• ISSNs: 0264-1275

Abstract

Abstract: The magnetron sputtered Al–Zr and Al–Zr–Si coatings were heat treated in-situ in a transmission electron microscope as well as ex-situ to observe their annealing behaviour and phase transformations. The samples were heated up to a temperature of 550 °C and then cooled to room temperature. A layered structure with alternating layers of Al and Zr/Si rich Al was found for the as deposited sputter coatings. During in-situ heat treatment, the phases formed in the coatings were analysed using selective area electron diffraction and energy dispersive X-ray spectroscopy. For the Al–Zr sputtered coatings, metastable L12 –Al3 Zr nucleated initially by splitting of Zr rich Al layers followed by transformation to equilibrium DO23 –Al3 Zr. Addition of Si to the Al–Zr sputtered coating resulted in the formation of DO22 –Al2.6 Si0.4 Zr phase instead of the DO23 –Al3 Zr phase. The lattice parameters and compositions of different phases formed are measured and presented. Graphical abstract: Highlights: Al–Zr and Al–Zr–Si coatings deposited using DC Magnetron sputtering showed a multi-layered structure. In-situ TEM and ex-situ heat treatment at 550 °C showed formation of DO23 –Al3 Zr with needle shape, and fine L12 –Al3 Zr phase with spheroidal shape. Addition of Si promoted the formation of DO22 –Al2.6 7Si0.4 Zr phase with spheroidal morphology. Metastable L12 –Al3 Zr nucleates first by splitting of Zr rich Al layers and then transformation to equilibrium DO23 –Al3 Zr. Al–Zr coatings were stable up to 400 °C, while Al–Zr–Si coatings showed L12 –Al3 Zr phase precipitation during sputter deposition.