Wear and Corrosion Resistance of Al0.5CoCrCuFeNi High-Entropy Alloy Coating Deposited on AZ91D Magnesium Alloy by Laser Cladding.

Kaijin Huang,Shihao Tang,Lin Chen,Feilong Du,Haisong Huang,Xin Lin

doi:10.3390/e20120915

Abstract

In order to improve the wear and corrosion resistance of an AZ91D magnesium alloy substrate, an Al0.5CoCrCuFeNi high-entropy alloy coating was successfully prepared on an AZ91D magnesium alloy surface by laser cladding using mixed elemental powders. Optical microscopy (OM), scanning electron microscopy (SEM), and X-ray diffraction were used to characterize the microstructure of the coating. The wear resistance and corrosion resistance of the coating were evaluated by dry sliding wear and potentiodynamic polarization curve test methods, respectively. The results show that the coating was composed of a simple FCC solid solution phase with a microhardness about 3.7 times higher than that of the AZ91D matrix and even higher than that of the same high-entropy alloy prepared by an arc melting method. The coating had better wear resistance than the AZ91D matrix, and the wear rate was about 2.5 times lower than that of the AZ91D matrix. Moreover, the main wear mechanisms of the coating and the AZ91D matrix were different. The former was abrasive wear and the latter was adhesive wear. The corrosion resistance of the coating was also better than that of the AZ91D matrix because the corrosion potential of the former was more positive and the corrosion current was smaller.

Highlights

High-entropy alloys are a new kind of alloy with excellent properties such as good wear resistance, excellent corrosion resistance, excellent oxidation resistance, low electrical conductivity, low thermal conductivity, and low coefficient of thermal expansion; they were invented by Yeh in 1995 [1,2,3,4,5,6,7]
“the smaller the corrosion current and the higher the corrosion potential, the better the corrosion resistance of the material” to evaluate the corrosion resistance of the active dissolved material, it can be seen that the corrosion resistance of the Al0.5 CoCrCuFeNi high-entropy alloy coating prepared by laser cladding was better than that of the AZ91D matrix
This is reflected by the fact that the former had a significantly higher corrosion potential (Ecorr = −0.998 V) than did the latter (Ecorr = −1.46 V), resistance of the material” to evaluate the corrosion resistance of the active dissolved material, it can be seen that the corrosion resistance of the Al0.5CoCrCuFeNi high-entropy alloy coating prepared by laser cladding was better than that of the AZ91D matrix

Summary

Introduction

High-entropy alloys are a new kind of alloy with excellent properties such as good wear resistance, excellent corrosion resistance, excellent oxidation resistance, low electrical conductivity, low thermal conductivity, and low coefficient of thermal expansion; they were invented by Yeh in 1995 [1,2,3,4,5,6,7]. They are composed of five or more elements in the same or an approximately equal molar ratio and have simple BCC and/or FCC solid solution phases. The microstructure, wear behavior, and corrosion behavior of the coating are shown in detail

Experimental

Microstructure and Microhardness

Results

XRD patterns of a laser-clad

Corrosion Properties

Conclusions