Investigation into corrosion and wear behaviors of laser-clad coatings on Ti6Al4V

Abstract

TiAlCoCrxFeNihigh-entropy alloys (HEAs) coatings were fabricated on the surface of Ti6Al4V by laser cladding. Their microstructural evolution with the increase in x value (x = 0, x = 1.0, x = 2.0) was investigated in detail. Besides that, the investigation into the effects of the Cr content on their corrosion behaviors and mechanical properties (in terms of hardness and wear resistance) was also carried out comprehensively. The results indicated that two kinds of phases (a solid solution with thehexagonal close-packed (HCP) structureand Ti2Ni) were synthesized in the coatings, and the HCP content was gradually increased with the increase in x accompanied with the decrease in Ti2Ni content. A HEA coating only composed of single HCP was successfully prepared when x reached 2.0. The electrochemical and immersion tests all confirmed that the coating with x = 2.0demonstrated the most excellent corrosion resistance in a0.1 mol•L-1 HCl solution from different aspects including corrosion tendency and corrosion rate without the applied potential, the formation difficult/stability of the passive film and the dissolution rate in the passive state, and corrosion surface morphology. The averagemicrohardness values of the coatings weregraduallyincreasedfrom 656HV0.2 to 800 HV0.2with increasing xfrom 0 to 2.0, which wereabout double that of the substrate (350 HV0.2). Wear resistance of the coatings also exhibited the upward tendency with increasing the x values (0.562 mm3 at x = 2.0, 0.640 mm3 at x = 1.0, 0.641 mm3 at x = 0 and 1.419 mm3 for the substrate). More Cr addition into the cladding material will contribute to the formation of a HEA coating composed of single HCPwith excellent corrosion and wear resistance.