Optimizing the microstructural evolution and wear performance of cold-sprayed Ti6Al4V-TiNp coatings by heat treatment

To enhance the wear resistance of cold-sprayed titanium coatings, a hybrid technique combining initial laser processing with subsequent micro-forging assisted cold spraying was employed to fabricate a highly relative density (99.35%) Ti6Al4V-TiNp composite coating. The regulation mechanisms of solid-solution and aging heat treatment on its microstructure and wear performance were systematically investigated. The robust metallurgical bonding between TiN particles and the titanium matrix is facilitated by the in-situ formation of the Ti 2 N phase under the optimized heat treatment regime (HT2: 850 °C solution treatment followed by 550 °C aging), and the cohesive strength among Ti6Al4V powder particles is also improved. Dispersed intragranular β-Ti nanocrystals and intergranular β laths are precipitated in the matrix, and the strengthening and toughening design of the matrix is achieved via the Orowan looping mechanism and the inherent plasticity of the β phase itself. Under the HT2 regime, the composite coating achieved the highest microhardness (reaching 558.03 HV) and optimal wear resistance. Its wear rate was as low as 0.46×10 -4 mm 3 /(N⋅m), representing reductions of 77.1% and 72.1% compared to the Ti6Al4V sheet and the as-sprayed coating, respectively. The wear mechanism transitioned from the mixed mode dominated by particle detachment in the as-sprayed state to mild abrasive wear characterized by the formation of a continuous protective transfer film. The improved wear performance under HT2 is associated with the combined effects of enhanced interfacial bonding, matrix strengthening, and increased coating hardness.