Microstructure and Corrosion Behavior of Atmospheric Plasma Sprayed NiCoCrAlFe High Entropy Alloy Coating

Area of Science:

• Materials Science
• Corrosion Engineering
• Surface Engineering

Background:

• High entropy alloys (HEAs) are advanced materials with exceptional properties.
• Thermal sprayed coatings offer protective surface solutions.
• Investigating HEAs in coating form is crucial for industrial applications.

Purpose of the Study:

• To develop a novel method for synthesizing high entropy alloy coatings.
• To evaluate the microstructure, phase formation, and corrosion resistance of these coatings.
• To compare the performance of annealed HEA coatings against non-annealed and substrate materials.

Main Methods:

• Atmospheric plasma spraying of HEA coatings onto Stainless Steel 316L substrates.
• Post-deposition annealing at 1000 °C for 4 hours.
• Microstructural analysis using Scanning Electron Microscopy (SEM).
• Phase identification via X-ray Diffraction (XRD).
• Potentiodynamic corrosion testing in 3.5% NaCl solution.

Main Results:

• Successful formation of HEA coatings with mixed BCC and FCC structures after annealing.
• Annealed HEA coatings exhibited significantly enhanced corrosion resistance (0.83 mpy).
• Non-annealed coatings (7.60 mpy) and SS 316L (3.04 mpy) showed lower corrosion resistance.

Conclusions:

• The developed synthesis method effectively produces high entropy alloy coatings.
• Annealing is critical for achieving the desired HEA structure and superior corrosion performance.
• These HEA coatings show great promise for corrosion protection applications.