Investigation into tribocorrosion behaviors of CoCrFeNiNb laser-clad coatings with Y₂O₃

Abstract Some components made of titanium alloys will serve in corrosive environments in the industry, and suffer from corrosion and wear at the same time. However, the components exhibit the high wear and corrosion rates due to their low hardness and the extremely thin oxidation film formed on their surfaces, which can accelerate their failure and reduce their service life. In response to this situation, CoCrFeNiNb high-entropy alloys (HEAs) coatings with Y 2 O 3 (0 wt%, 1 wt%, 2 wt%, and 3 wt%) were successfully prepared on Ti6Al4V by laser cladding. The effects of Y 2 O 3 addition content on the microstructure, corrosion and mechanical properties were investigated comprehensively by x-ray diffractometry (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), microhardness tests, electrochemical tests and tribocorrosion tests in this work. Other than them, tribocorrosion behaviors of the coatings were especially highlighted in two different environments (neutral (pH 7) and acid (pH 3) solutions). The results showed the significant enhancement in microhardness with the introduction of Y 2 O 3 due to the microstructural refinement and the formation of Laves phase Cr 2 Nb in the coatings. The coating with 2 wt% Y 2 O 3 performed the most excellent corrosion resistance (neutral solution: E corr = −0.12 V; acid solution: E corr = 0.043 V) increased by 55.5% and 115.0% of the coating without Y 2 O 3 . As well as, the coating also demonstrated the lowest wear rates (neutral solution: 3.32 × 10 −4 mm 3 ·N −1 ·m −1 ; acid solution: 2.24 × 10 −4 mm 3 ·N −1 ·m −1 ) reduced by 17.8% and 33.3% of the coating without Y 2 O 3 . The superior tribocorrosion resistance and corrosion resistance make CoCrFeNiNb+2 wt% Y 2 O 3 HEA coating show a tremendous potential in aerospace and marine applications.