Microstructure and Wear Behavior of FeCoCrNiMo0.2 High Entropy Coatings Prepared by Air Plasma Spray and the High Velocity Oxy-Fuel Spray Processes

Tianchen Li,Liyou Xu,Wenmin Guo,Bin Liu,Yong Liu

doi:10.3390/coatings7090151

Tianchen Li, Liyou Xu + Show 3 more

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https://doi.org/10.3390/coatings7090151

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Journal: Coatings	Publication Date: Sep 20, 2017
Citations: 64	License type: CC BY 4.0

Affiliation: Central South University, Shaoyang University

Abstract

In the present research, the spherical FeCoCrNiMo0.2 high entropy alloy (HEA) powders with a single FCC solid solution structure were prepared by gas atomization. Subsequently, the FeCoCrNiMo0.2 coatings with a different content of oxide inclusions were prepared by air plasma spraying (APS) and high-velocity oxy-fuel spraying (HVOF), respectively. The microstructure, phase composition, mechanical properties, and tribological behaviors of these HEA coatings were investigated. The results showed that both HEA coatings showed a typical lamellar structure with low porosity. Besides the primary FCC phase, a mixture of Fe2O3, Fe3O4, and AB2O4 (A = Fe, Co, Ni, and B = Fe, Cr) was identified as the oxide inclusions. The oxide content of the APS coating and HVOF coating was calculated to be 47.0% and 12.7%, respectively. The wear resistance of the APS coating was approximately one order of magnitude higher than that of the HVOF coating. It was mainly attributed to the self-lubricated effect caused by the oxide films. The mass loss of the APS coating was mainly ascribed to the breakaway of the oxide film, while the main wear mechanism of the HVOF coating was the abrasive wear.

Highlights

In 2004, Yeh [1] first proposed a new multi-component alloy design concept named high-entropy alloys (HEAs), which broke the conventional one or two major elements alloying design strategy
Except for the presence of oxygen, the results indicated that no obvious changes could be detected in Except for the presence of oxygen, the results indicated that no obvious changes could be detected the chemical composition between the feedstock powders and the metal phase included in the asin the chemical composition between the feedstock powders and the metal phase included in the sprayed coatings
The FeCoCrNiMo0.2 high entropy alloy coatings were successfully prepared with the air plasma spraying (APS) and high-velocity oxy-fuel spraying (HVOF) spray techniques

Summary

Introduction

In 2004, Yeh [1] first proposed a new multi-component alloy design concept named high-entropy alloys (HEAs), which broke the conventional one or two major elements alloying design strategy. Compared with the conventional alloys, the most distinguished effects in HEAs are high-entropy, severe lattice distortion, sluggish diffusion, and cocktail effects These effects might provide several important advantages including ease of getting the supersaturated state and fine precipitates, an increased recrystallization temperature, slower grain growth, a reduced particle coarsening rate, and an increased creep resistance, which might be beneficial for high mechanical properties, superior thermal stability, and excellent wear- and corrosion-resistance [3,5,6,7,8]. These outstanding properties were desirable for engineering applications, such as machinery, furnace parts, and even space [9]

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