Laves phase tailored heterostructures for excellent tribocorrosion resistance in a laser cladding Ti-based composite coating

To improve the tribocorrosion resistance of titanium alloy, a Ti-based composite coating was successfully fabricated on TC4 titanium alloy by laser cladding. It produces a refined multiphase microstructure consisting of a β-Ti matrix, carbide reinforcements, and finely dispersed Laves (NbCr 2 ) phases, accompanied by significant grain refinement. This heterogeneous structure activates dense dislocation networks and stratification faults, accommodates plastic deformation while effectively suppressing the nucleation and propagation of fatigue cracks. It enables an exceptional synergy between hardness (727.2 HV 0.3 ) and fracture toughness (8.27 MPa·m 1/2 ). Of the coatings examined, the 10% Nb alloy exhibited the best tribocorrosion performance, with a wear rate of 8.81 × 10 -5 mm 3 /(N·m) and a corrosion current density of 1.18 ×10 -8 A/cm 2 . Meanwhile, the formation of a dense, self-healing composite passive film enriched with TiO 2 , Cr 2 O 3 , and Nb 2 O 5 markedly suppresses electrochemical dissolution. This study establishes a microstructure-driven design strategy for breaking the toughness–wear-corrosion trade-off in Ti-based coatings.