Corrosion behavior of Al0.4CoCu0.6NiSi0.2Ti0.25 high-entropy alloy coating via 3D printing laser cladding in a sulphur environment

High-entropy alloys (HEAs) are of great interest in materials science and engineering communities owing to their unique phase structure. HEAs are constructed with five or more principal alloying elements in equimolar or near-equimolar ratios. Therefore, they can derive their performance from multiple principal elements rather than a single element. In this work, three-dimensional printing laser cladding was applied to produce an Al0.4CoCu0.6NiSi0.2Ti0.25 HEA coating. The experimental results confirmed that the laser cladding could be used to produce a thin coating of 120 mu m in thickness. In the high-temperature laser cladding process, some Fe elements diffused from the substrate to the coating, forming a combination of face-centred cubic and body-centred cubic phase structures. The HEA coating metallurgically bonded well with the substrate. Owing to the increased dislocation density and number of grain boundaries, the HEA coating was harder and had a stronger hydrophobicity than X70 steel. The electrochemistry results showed that the HEA coating had better corrosion resistance than X70 steel. Aluminium oxides formed on the surface of the HEA coating had a certain protective effect. However, because of the laser cladding, the HEA coating generated cracks. In future work, the laser cladding technology will be improved and heat treatment will be implemented to prevent formation of cracks. (C) 2020 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

Automated summary

High-entropy alloys (HEAs) are composed of multiple principal alloying elements, exhibiting unique phase structures and excellent performance. Laser cladding technology can be used to produce HEA coatings with good metallurgical bonding and corrosion resistance. Future work will focus on improving laser cladding technology to prevent crack formation.