Swinburne University of Technology, Hawthorn

Understanding the Microstructural Evolution of High Entropy Alloy Coatings Manufactured by Atmospheric Plasma Spray Processing

EVENT DETAILS

Ameey Anupam presented her current research project on atmospheric plasma spray (APS) of mechanically alloyed equiatomic AlCoCrFeNi high entropy alloy (HEA) results in a complex alloy-oxide coating. All the constituent phases have been identified via extensive microscopy and spectroscopy at various length scales. This microstructural characterization along with the in-flight particle size and temperature measurements and single-pass studies have been used to decode the particle-plasma-atmosphere interaction that resulted in the observed coating microstructure. Particles finer than 5 µm diameter are expected to melt, spheroidize and oxidize completely in-flight when closer to the plasma plume core, whereas those larger than 15 µm only exhibit softening and surface oxidation. Molten particles splat on impact resulting in typical lamellar microstructure, while the unmelted particles either get embedded in the coating or bounce off the substrate. Equiatomic AlCoCrFeNi powder oxidizes differently in plasma in air than the cast alloy during isothermal oxidation, resulting in multiple oxides – alumina, chromia, spinels and residual unoxidized alloy cores.  Understanding these phenomena in conjunction with each other enables us to tailor feedstock and spray parameters to get the desired coating properties.

Ameey Anupam is a PhD Candidate as part of the partnered PhD program with Swinburne University of Technology and the Indian Institute of Technology Madras, India. Her supervisors are Distinguished Professor Christopher Berndt (Swinburne) and Professor Ravi S. Kottada (IIT Madras) and Professor B.S. Murty (IIT Madras). Ameey completed a Bachelor of Technology with Honours in metallurgical and materials engineering from the National Institute of Technology Jamshedpur, India. Her research is focussed on developing thermal sprayed high entropy alloy coatings for high temperature applications and decoding the science governing them.

DATE

22 November 2019


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