Improvement of hardness and wear resistance in SiC/Ti–6Al–4V surface composites fabricated by high-energy electron beam irradiation

This study is concerned with the microstructural analysis and the improvement of hardness and wear resistance of SiC/Ti–6Al–4V surface composites fabricated by high-energy electron beam. The mixtures of SiC, SiC+TiC, or SiC+Ti powders and CaF2 flux were deposited on a Ti–6Al–4V substrate, and then electron beam was irradiated on these mixtures. In the specimens processed with flux addition, the surface composite layers of 1.7–2.1 mm in thickness were homogeneously formed without defects, and contained a large amount (over 44 vol.%) of precipitates such as Ti5Si3 and TiC in the martensitic matrix. This microstructural modification including the formation of hard precipitates and hardened matrix in the surface composite layers could be explained from a Ti–Si–C ternary phase diagram, and greatly improved hardness and wear resistance 2 and 5–25 times higher than the Ti alloy substrate, respectively. These findings suggested that high-energy electron beam irradiation was useful for the development of Ti-base surface composites with improved hardness and wear properties.