Influence of microstructures and wear behaviors of the microalloyed coatings on TC11 alloy surface using laser cladding technique

Microalloyed coatings were fabricated on a forged TC11 titanium alloy surface by adding different amount of ZrN powders using laser cladding technique. Microstructures of coatings and heat affect zone were systematically investigated with the study of microhardness as well as wear property. Results indicated that all coatings have very uniform equiaxial grains with very fine α + β two-phase microstructure (the thickness of α lamellar is 0.8 μm), and nearly no change of microstructure for coatings was observed with the increase contents of ZrN from 3 wt% to 12 wt%. The changes of microstructure from coating to substrate are: fine α + β two-phase structure, super fine α + β two-phase structure (α lamellar of 0.2 μm), α_p + α_s + β structure, and α + β (forged). By increasing the contents of Zr and N, the hardness of coatings increased accordingly with no suddenly change at the interfacial region. Due to the strong solid-solution strengthening, coatings maintain high hardness even coarsening their microstructures. The enhanced hardness of coatings largely improves the wear properties of alloys to only more than twice of the TC11 matrix when addition of 12 wt% ZrN.