title: Structural and mechanical evolution of reactively and non-reactively sputtered Zr-Al-N thin films during annealing.
abstract: The influence of reactive and non-reactive sputtering on structure, mechanical properties, and thermal stability of Zr1 - xAlxN thin films during annealing to 1500 °C is investigated in detail. Reactive sputtering of a Zr0.6Al0.4target leads to the formation of Zr0.66Al0.34N thin films, mainly composed of supersaturated cubic (c) Zr1 - xAlxN with small fractions of (semi-)coherent wurtzite (w) AlN domains. Upon annealing, the formation of cubic Zr-rich domains and growth of the (semi-)coherent w-AlN domains indicate spinodal-like decomposition. Loss of coherency can only be observed for annealing temperatures above 1150 °C. Following these decomposition processes, the hardness remains at the as-deposited value of ~ 29 GPa with annealing up to 1100 °C. Using a ceramic (ZrN)0.6(AlN)0.4target and sputtering in Ar atmosphere allows preparing c-Zr0.68Al0.32N coatings with a well-defined crystalline single-phase cubic structure combined with higher hardnesses of ~ 31 GPa. Due to the absence of (semi-)coherent w-AlN domains in the as-deposited state, which could act as nucleation sites, the decomposition process of c-Zr1 - xAlxN is retarded. Only after annealing at 1270 °C, the formation of incoherent w-AlN can be detected. Hence, their hardness remains very high with ~ 33 GPa even after annealing at 1200 °C. The study highlights the importance of controlling the deposition process to prepare well-defined coatings with high mechanical properties and thermal stability.
authors.affiliation: Institute of Materials Science and Technology, Vienna University of Technology, A-1040 Vienna, Austria.
authors.forename: P H
authors.initials: PH
authors.lastname: Mayrhofer
authors.affiliation: Department of Physical Metallurgy and Materials Testing, Montanuniversität Leoben, A-8700 Leoben, Austria.
authors.forename: D
authors.initials: D
authors.lastname: Sonnleitner
authors.affiliation: Institute of Materials Science and Technology, Vienna University of Technology, A-1040 Vienna, Austria.
authors.forename: M
authors.initials: M
authors.lastname: Bartosik
authors.affiliation: Department of Physical Metallurgy and Materials Testing, Montanuniversität Leoben, A-8700 Leoben, Austria.
authors.forename: D
authors.initials: D
authors.lastname: Holec
keywords: Age-hardening; DSC; Decomposition; Non-reactive sputtering; ZrAlN
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