Microstructure and thermal stability of corundum-type (Al0.5Cr0.5)(2)O-3 solid solution coatings grown by cathodic arc evaporation

作者：Edlmayr V; Pohler M; Letofsky Papst I; Mitterer C^*

来源：Thin Solid Films, 2013, 534: 373-379.

DOI：10.1016/j.tsf.2013.02.046

• (Al, Cr)(2)O-3
• Al-Cr-O
• Arc evaporation
• Coatings
• Annealing
• Thermal stability

Corundum-type (AlxCr1-x)(2)O-3 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)(2)O-3 solid solution shows a miscibility gap below 1300 degrees 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)(2)O-3 solid solution, with smaller fractions of cubic (AlxCr1-x)(2)O-3. An additional Al-rich amorphous phase and a Cr-rich crystalline phase stem from the droplets incorporated. The corundum-type (AlxCr1-x)(2)O-3 solid solution is still present after vacuum annealing at 1050 C for 2 h, whereas the cubic (AlxCr1-x)(2)O-3 phase has transformed to corundum-type (AlxCr1-x)(2)O-3. Cr and Cr2O3 have been detected in the annealed coating, the latter most probably originating from the partial oxidation of Cr-rich droplets. Upon crystallization of the amorphous phase fractions present, gamma-Al2O3 is formed, which then transforms into alpha-Al2O3. No evidence for decomposition of the corundum-type (AlxCr1-x)(2)O-3 solid solution could be found within the temperature range up to 1400 degrees C.

• 出版日期2013-5-1