Microstructures and oxidation behavior of Al-CrMnFeCoMoW composite coatings on Ti-6Al-4V alloy substrate via high-energy mechanical alloying method.

Abstract In the present work, CrMnFeCoMoW high entropy alloy powder and Al- CrMnFeCoMoW composite coatings were successfully synthesized on Ti-6Al-4V alloy substrate via mechanical alloying method. The final milling products for as-milled CrMnFeCoMoW high entropy alloy powder consist of body-centered cubic (BCC) and face-centered cubic (FCC) solid solution phases. The composite coatings exhibit a composite structure consisting of white high entropy alloy particles and Al-rich gray regions. The adhesion of the coating was tested by scratch experiment. The effects of the ratio of Al-CrMnFeCoMoW powder ratio and milling time on the preparation of composite coatings were investigated. The microstructure and element distribution and phase composition of the coating had been studied. The results show that under the optimal parameters, the thickness of the coating is 180 μm, which shows a good bonding with the Ti-6Al-4V alloy substrate. The high temperature cyclic oxidation test was carried out at 850 °C. The oxidation resistance of the coating was compared with that of the traditional oxidation resistant coating. The composite coating obviously exhibits better oxidation resistance than traditional coating. Highlights • A composite coating on high entropy alloy was prepared by mechanical alloying. • The coating is a composite structure composed of white particles and gray areas. • Effects of Al-CrMnFeCoMoW powders ratio and milling time on the fabrication of composite coating were investigated. • The oxidation resistance of the coating was tested and the mechanism of oxidation resistance was analyzed. [ABSTRACT FROM AUTHOR]