Tribo-corrosion is an issue of concern for marine and other fluid machinery. High entropy alloys (HEAs) represent a new category of materials possessing exceptional properties. We investigated the erosion-corrosion behavior of Al0.1CoCrFeNi HEA. For comparison, stainless steel SS316L is also evaluated. Results indicate that despite low hardness and yield strength, HEA exhibits high erosion-corrosion resistance compared to steel. The HEA also shows high pitting and passive potentials compared to steel. The superior erosion-corrosion resistance of HEA is due to high corrosion resistance, and work hardenability. The degradation mechanism investigated using SEM show ploughing as the primary material removal mode (MRM) for HEA at an oblique angle compared to micro-cutting for SS316L steel. At normal impingement, platelet mechanism is observed to be the dominant MRM. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Harpreet Singh

Mechanical Engineering

(SoE) School of Engineering

Harpreet Singh Grewal

Nair R.B.

Ayyagari A.

Mukherjee S.

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Shiv Nadar University

Advanced Engineering Materials

In present work, we investigated the tribological behavior of the high entropy alloy (HEA) claddings under different degrading environments viz, slurry erosion-corrosion, liquid impingement erosion, electrochemical corrosion, and sliding wear. The HEA claddings were developed by varying Al fraction (AlxCoCrFeNi) (x = 0.1 to 3) using microwave processing. The claddings were composed of cellular structure with intermetallic phases segregated in the intercellular region. Variation in Al content showed significant influence on the microstructure and mechanical properties. The hardness of the claddings increased with an increase in Al fraction with a maximum value of 624 HV observed for the cladding containing three molar Al. Correspondingly, the fracture toughness showed an opposing trend. All claddings showed better wear resistance than SS316L with equimolar composition outperforming other counterparts. The equimolar HEA cladding showed 3 to 23 times higher wear resistance compared to SS316L steel depending upon test conditions. Inimitable wear resilience of the equimolar composition was attributed to its high hardness and strain-hardening ability. Surface morphologies of the tested claddings indicated the presence of ductile-brittle mixed damage modes. The tested surfaces showed numerous pits and cracks with delaminated secondary phase. Presence of groves and signs of delamination were also observed in case of sliding wear. The results of the present work show that microwave synthesized equimolar HEAs can effectively counter different tribological forms. © 2019 Elsevier B.V.

Wear

Tribological behavior of microwave synthesized high entropy alloy claddings

There has been tremendous interest in recent years in a new class of multi-component metallic alloys that are referred to as high entropy alloys, or more generally, as complex concentrated alloys. These multi-principal element alloys represent a new paradigm in structural material design, where numerous desirable attributes are achieved simultaneously from multiple elements in equimolar (or near equimolar) proportions. While there are several review articles on alloy development, microstructure, mechanical behavior, and other bulk properties of these alloys, then there is a pressing need for an overview that is focused on their surface properties and surface degradation mechanisms. In this paper, we present a comprehensive view on corrosion, erosion and wear behavior of complex concentrated alloys. The effect of alloying elements, microstructure, and processing methods on the surface degradation behavior are analyzed and discussed in detail. We identify critical knowledge gaps in individual reports and highlight the underlying mechanisms and synergy between the different degradation routes. © 2018 by the authors. Licensee MDPI, Basel, Switzerland.

Fulltext

Metals

Corrosion, erosion andwear behavior of complex concentrated alloys: A review

High entropy alloys (HEAs) represent a new paradigm of structural alloys comprising of multiple principal elements in equimolar or near-equimolar concentration. The superior corrosion and oxidation resistance of HEAs at high temperature make them attractive for several structural applications. In this context, erosion behavior of HEAs has been largely unexplored. In this study, the slurry erosion performance of single phase Al0.1CoCrFeNi high entropy alloy was investigated. For comparison, mild steel and stainless steel (SS316L) were also investigated under similar conditions. The slurry erosion was conducted at different impingement angles and at a constant velocity of 20 m/s. The microstructural and mechanical characterization were conducted using scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), x-ray diffraction (XRD), nanoindentation and micro-hardness testing. Similar to the mild steel and stainless steel, HEA also showed ductile mode of erosion. The erosion rate for HEA was found to be higher compared to stainless steel, however in spite of lower tensile strength and hardness, HEA exhibited higher erosion resistance compared to mild steel. The high erosion resistance of HEA compared to mild steel is explained on the basis of its work hardening behavior, low stacking fault energy, and superior corrosion resistance. Erosion response of the investigated materials showed significant correlation with ultimate strength and ultimate resilience. In depth analysis of the eroded HEA samples showed ploughing as the prominent material removal mechanism at oblique angles compared to micro-cutting for SS316L and mild steel. In contrast, highly deformed and work-hardened platelets were observed at normal impingement angle for all materials. © 2017 Elsevier B.V.

Slurry erosion behavior of high entropy alloys

Journal of Alloys and Compounds

Phase evolution and cavitation erosion-corrosion behavior of FeCoCrAlNiTi x high entropy alloy coatings on 304 stainless steel by laser surface alloying

Erosion-wear and intergranular corrosion resistance properties of AISI 304L austenitic stainless steel after low-temperature plasma nitriding

Materials Science and Technology

On the microstructure and erosion–corrosion resistance of AlCrFeCoNiCu high-entropy alloy via annealing treatment

Tribology Transactions

Slurry Erosion Resistance of Laser Clad NiCoCrFeAl3High-Entropy Alloy Coatings

High Entropy Alloys: Prospective Materials for Tribo-Corrosion Applications