Microstructure and tribological properties of laser in-situ synthesized Ti3Al composite coating on Ti-6Al-4V

Abstract Titanium intermetallics are highly significant to protect surfaces of lightweight structures against corrosion and wear. In this study, Ti and Al powders were uniformly mixed with an atomic ratio 65:35 and in-situ synthesized on Ti-6Al-4V substrate by laser cladding with Ar cooling. The microstructure and high temperature tribological behavior were studied. The results show that Ti3Al (α2) phase was first precipitated in the form of coarse primary dendrites during cladding solidification, and subsequently α-Ti (α) phase of needle-shaped martensite was formed by fast cooling. The 6:4 ratio of phase α2 to α of the composite coating provides optimal toughness and high hardness (680 HV). Under the testing up to 500 °C, the average friction coefficient of the composite coating is 0.22 ± 0.011 and a 35% lower wear rate than that of Ti-6Al-4V substrate.