Effects of Silicon and Titanium Addition on the Corrosion and Wear Behavior of Plasma-Sprayed Al0.4CoCu0.6Ni-Based High-Entropy Alloy Coatings

The AlCoCuNi-based (Al0.4CoCu0.6NiSi0.2, Al0.4CoCu0.6NiTi0.2 and Al0.4CoCu0.6NiSi0.2Ti0.2) high-entropy alloy (HEA) coatings were prepared by atmospheric plasma spraying using gas-atomized alloy powders. The effects of Si and Ti alloying elements addition on the microstructure, microhardness, corrosion resistance and wear resistance of the AlCoCuNi-based HEA coatings were investigated. The results show that the dendrite and interdendritic phases are formed in the AlCoCuNiSi and AlCoCuNiSiTi HEA powders owing to the segregation of elements. The AlCoCuNiSi and AlCoCuNiTi HEA powders and coatings are of single-phase FCC structure, while the AlCoCuNiSiTi transforms from equivalent of FCC and BCC phases to a majority BCC phase with minor amount of FCC phase after plasma spraying. The corrosion current densities of AlCoCuNiTi and AlCoCuNiSiTi HEA coatings are significant lower than that of AlCoCuNiSi HEA coating, demonstrating that the addition of Ti is better than Si in improving the corrosion resistance. However, the incorporation of Si is more effective than Ti in reducing the friction coefficient and wear rate, because the AlCoCuNiSiTi presents the lowest friction coefficient and wear rate, followed by AlCoCuNiSi and AlCoCuNiTi HEA coatings.

Automated summary

In this study, AlCoCuNi-based high-entropy alloy coatings were prepared by atmospheric plasma spraying. The effects of Si and Ti alloying elements on the microstructure, microhardness, corrosion resistance, and wear resistance of the coatings were investigated. The results showed that Ti addition improved the corrosion resistance, while Si addition reduced the friction coefficient and wear rate.