Tribological and corrosion performance of an atmospheric plasma sprayed AlCoCr0.5Ni high-entropy alloy coating

Meghwal, Ashok and Anupam, Ameey and Schulz, Christiane and Hall, Colin and Murty, B S and et al, . (2022) Tribological and corrosion performance of an atmospheric plasma sprayed AlCoCr0.5Ni high-entropy alloy coating. Wear, 506-50. pp. 1-15. ISSN 0043-1648

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Abstract

High entropy alloys (HEAs) are an established new class of materials exhibiting excellent mechanical and functional properties. The well-studied AlCoCrFeNi HEA has been modified to AlCoCr0.5Ni HEA in view of the latter's better oxidation resistance. The elimination of Fe and reduction in Cr content is expected to improve the HEA's corrosion and tribological performance. Thus, an AlCoCr0.5Ni HEA coating was fabricated via the atmospheric plasma spray (APS) process using mechanically alloyed (MA) feedstock. The microstructural characteristics of both the MA feedstock and coating have been investigated. The sliding wear behaviour of the HEA coating was evaluated at both room temperature and 500 °C. In addition, the electrochemical compatibility of the coating was analyzed in seawater. The microstructural results revealed that the MA feedstock was composed of BCC/B2 and FCC phases, which were retained in the HEA coating along with minor oxides. The wear resistance of the AlCoCr0.5Ni HEA coating was superior to the AlCoCrFeNi HEA coating both at room temperature and 500 °C. The high wear resistance of the coating was attributed to the formation of equal concentrations of the BCC/B2 and FCC phases. The coating exhibited a greater tendency of being cathodic (passive) than both an AlCoCrFeNi HEA coating and SS316L with identical polarization behaviour. © 2022

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IITH Creators:

IITH Creators	ORCiD
Murty, B S	https://orcid.org/0000-0002-4399-8531

Item Type:

Article

Additional Information:

On the other hand, at 500 °C, the coating surface was initially heated to and then stabilized at 500 °C, which would have stimulated tribo-chemical reactions, developing a thin and dense tribo-oxide film, preventing initial direct contact of the counter body with the coating surface, Fig. 11(c). However, this oxide layer cracks through repeated loading and exposes the HEA splats to the counter body. The direct exertion of the loading force preceded the spallation of the weakly bonded HEA splats due to the surface fatigue, thus forming the spalling pits. The continuous heating of the coating surface, in conjunction with the additional frictional heating at the counter body-coating surface interface, supported the continual development of a compacted and lubricious oxide layer, enhancing the anti-wear property of the HEA coating, Fig. 11(d). The wear resistance of the coating was also enhanced by mechanical mixing of oxide generated debris on the worn surface, which simultaneously rolled between the coating surface and counter body, preventing the direct contact between the two bodies, thereby reducing overall coating mass loss. In addition, the temperatures experienced by the coating during the HT wear testing are likely to promote sintering, which strengthens the interlamellar bonding between the flattened splats. This would further improve the mechanical properties of the coating, as evident by the increase in hardness after HT wear testing, which eventually enhances the wear resistance of the HEA coating [39]. Overall, abrasive wear in conjunction with fatigue wear contributed to the coating mass loss during 500 °C sliding wear testing conditions.This work is supported under a Swinburne University Postgraduate Research Award (SUPRA). This study was also supported by the Australian Research Council (ARC) Discovery Project 2021 under project DP210103318 titled “Design of Non-Equilibrium Architectures: Leveraging High Entropy Materials” and under the Industrial Transformation Training Centre project IC180100005 that is titled “Surface Engineering for Advanced Materials”, SEAM. We are grateful for the additional support from the industrial, university and other organization partners who have contributed to the establishment and support of SEAM. The authors acknowledge the facilities, scientific and technical assistance of Microscopy Australia at the University of South Australia, a facility that is funded by the University of South Australia, the State and Federal Governments. This work was performed in part at the South Australian node of the Australian National Fabrication Facility under the National Collaborative Research Infrastructure Strategy.

Uncontrolled Keywords:

Atmospheric plasma spray (APS); Corrosion; High entropy alloys (HEAs); Microstructure; Wear

Subjects:

Others > Metallurgy
Materials Engineering > Materials engineering

Divisions:

Department of Material Science Engineering

Depositing User:

. LibTrainee 2021

Date Deposited:

16 Aug 2022 09:31

Last Modified:

16 Aug 2022 09:31