AVS 59th Annual International Symposium and Exhibition
    Advanced Surface Engineering Monday Sessions
       Session SE+NS-MoM

Paper SE+NS-MoM9
Thermal Stability of (AlxCr1-x)2O3 Solid Solution Coatings Grown by Cathodic Arc Evaporation

Monday, October 29, 2012, 11:00 am, Room 22

Session: Nanostructured Thin Films and Coatings I: Interface Aspects
Presenter: C. Mitterer, University of Leoben, Austria
Authors: V. Edlmayr, University of Leoben, Austria
M. Pohler, University of Leoben, Austria
I. Letofsky-Papst, Graz University of Technology, Austria
C. Mitterer, University of Leoben, Austria
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Corundum-type (AlxCr1-x)2O3 coatings were grown by reactive cathodic arc evaporation in an oxygen atmosphere using AlCr targets with an Al/Cr atomic ratio of 1. Since the (AlxCr1-x)2O3 solid solution shows a miscibility gap below 1300°C, where spinodal decomposition is predicted, the microstructural changes upon annealing were investigated by a combination of transmission electron microscopy, X-ray diffraction, Raman spectroscopy and differential scanning calorimetry. The as-deposited coating consists primarily of the corundum-type (AlxCr1-x)2O3 solid solution, with smaller fractions of cubic (AlxCr1-x)2O3. An additional Al-rich amorphous phase and a Cr-rich crystalline phase stem from the droplets incorporated. The corundum-type (AlxCr1-x)2O3 was still present after vacuum annealing at 1050°C for 2 hours, whereas additional α-Al2O3 and Cr2O3 phases were formed due to decomposition of the cubic (AlxCr1-x)2O3 phase. Likewise, Cr and Cr2O3 have been detected in the annealed coating, most probably originating from the partial oxidation of Cr-rich droplets. Upon crystallization of the amorphous phase fractions present, γ-Al2O3 is formed, which partially transforms in α-Al2O3. No evidence for decomposition of the corundum-type (AlxCr1-x)2O3 solid solution could be found within the temperature range up to 1400°C.