Effect of Heat Treatment Temperature on Microstructure and Mechanical and Tribological Properties of Cold Sprayed Ti-6Al-4V Coatings

In this study, Ti-6Al-4V (Ti-64) coatings were prepared on commercial Ti-64 substrates via a high-pressure cold spray process. The coatings were heat treated at different temperatures of 400-1000 degrees C to investigate the effect of heat treatment temperature on their microstructure and mechanical and tribological properties. The increased heat treatment temperature from 400 to 600 degrees C promoted diffusion between sprayed Ti-64 particles. Recrystallization of the sprayed particles was found at the heat treatment temperature of 800 degrees C and grain growth was found in the microstructure of the coating heat treated at 1000 degrees C. The highest and lowest hardnesses of the heat-treated coatings were found at heat treatment temperatures of 400 and 800 degrees C, respectively. Therefore, the lowest and highest specific wear rates of the coatings were consistently found at 400 and 800 degrees C due to their highest and lowest abrasive wear resistances associated with their highest and lowest surface hardnesses, respectively. The coating heat treated at 400 degrees C showed the highest surface hardness of 470.1 Hv and lowest specific wear rate of 69.6 x 10(-14) m(3)/Nm. It could be concluded that the microstructure and mechanical and tribological properties of the Ti-64 coatings were significantly influenced by heat treatment temperature.