AVS 66th International Symposium & Exhibition
    Advanced Surface Engineering Division Thursday Sessions
       Session SE-ThA

Paper SE-ThA7
Thermal Stability of MoNbTaVW High Entropy Alloys Thin Films Deposited by Cathodic Arc

Thursday, October 24, 2019, 4:20 pm, Room A215

Session: New Challenges and Opportunities in Surface Engineering
Presenter: Robert Franz, Montanuniversität Leoben, Austria
Authors: A. Xia, Montanuniversität Leoben, Austria
R. Franz, Montanuniversität Leoben, Austria
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High entropy alloys (HEAs) are a new emerging class of materials typically consisting of 5 to 13 metallic elements in an approximately equimolar ratio. Studies conducted on HEA bulk materials revealed promising combinations of properties, such as high strength, ductility, corrosion resistance, wear resistance, hardness, low diffusion and thermodynamic stability. While research on bulk high entropy alloys has seen quite a boost over the past years, investigations on thin films are still a relatively unexplored area.

Within the current work, the thermal stability of refractory MoNbTaVW HEA thin films was studied up to an annealing temperature of 1600 °C. The thin films with a thickness of about 1 µm were synthesized on sapphire substrates by cathodic arc deposition. The samples were annealed in a vacuum furnace for 1 hour at temperatures ranging from 1000 to 1600 °C in steps of 100 °C. After annealing, scanning electron microscopy images were recorded indicating changes in the film morphology at 1200 °C and above. Analysis by X-ray diffraction revealed the formation of new phases at 1500 °C. Nanoindentation tests were performed to assess possible changes in the mechanical properties of the films. A decrease from about 20 GPa for the as-deposited films to about 9 GPa after annealing at 1600 °C was noticed. The electrical conductivity of the MoNbTaVW thin film slightly decreased due to annealing as the measured resistivity increased from 5·10-7 Ωm to 1.5·10-6 Ωm.