| The present study is concerned with the microstructural analysis and the evaluation of hardness and wear properties of Ti-6Al-4V surface-alloyed materials fabricated by high-energy electron beam. The mixtures of TiC, TiN, or TiC+TiN powders and CaF₂ flux were deposited on a Ti-6Al-4V substrate, and then electron beam was irradiated on these mixtures using an electron beam accelerator. In the specimens processed with a flux mixing ratio of 50 wt.%, the surface-alloyed layers of 1 ㎜ in thickness were homogeneously formed without defects, and contained a large amount (over 30 vol.%) of precipitates such as TiC, TiN, (Ti_xAl(1-x).)N, and TiC_xN(1-x) in the martensitic or N-rich acicular α-Ti matrix. This microstructural modification including the formation of hard precipitates and hardened matrices in the surface-alloyed layers improved hardness and wear resistance. Particularly in the TiN/Ti surface-alloyed material, the wear resistance was greatly enhanced by ten times higher than that of the Ti alloy substrate. These findings suggested that the surface-alloying using high-energy electron beam irradiation was economical and useful for the development of titanium-base surface-alloyed materials with improved hardness and wear properties. |
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