Enhanced corrosion and wear resistance of a laser-cladded non-equimolar TiZrNbTaMo high-entropy alloy coating

Ti6Al4V titanium alloys are widely used in aerospace engineering due to their high specific strength and inherent surface oxidation protection capability. However, in chloride-rich marine environments, the surface oxide layer is prone to local breakdown, leading to severe corrosion and rapid degradation of structural components. To address this challenge, a non-equimolar TiZrNbTaMo high-entropy alloy (HEA) coating was designed and fabricated on a Ti6Al4V substrate via laser cladding, aiming to simultaneously enhance wear and corrosion resistance. The as-designed HEA formed a stable single-phase body-centered cubic (BCC) solid solution while suppressing Ta/Mo segregation during rapid solidification. Comprehensive characterization revealed that the coating possesses a dense microstructure and excellent interfacial integrity. Compared with Ti6Al4V, the coating exhibited an 81.5% reduction in wear rate, a significantly more positive corrosion potential (−0.412 V vs −0.717 V), and a one-order-lower corrosion current density (3.47 × 10 -6 A·cm -2 ). Electrochemical impedance spectroscopy confirmed a higher charge-transfer resistance (Rct = 3616 Ω·cm 2 ), while XPS analysis revealed a dual-layer oxide protective layer composed of outer high-valence oxides (TiO 2 , ZrO 2 , Nb 2 O 5 , Ta 2 O 5 , MoO 3 /MoO 2 ) and inner sub-oxides (ZrO X , NbO 2 ), which effectively inhibited Cl − penetration and enabled self-repassivation. After 360 h of salt-spray exposure, the coating surface remained compact with only isolated corrosion sites, whereas the Ti6Al4V substrate exhibited extensive pitting and cracking. The proposed strategy not only provides fundamental insights into multi-oxide protection behavior but also delivers engineering guidance for developing durable protective systems applicable to aerospace and marine environments.