Correlation of microstructure and abrasive and sliding wear resistance of (TiC,SiC)/Ti-6Al-4V surface composites fabricated by high-energy electron-beam irradiation |
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Authors: | Jun Cheol Oh Sunghak Lee |
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Affiliation: | (1) Department of Materials, University of Oxford, OX1 3PH Oxford, United Kingdom;(2) Center for Advanced Aerospace Materials, Pohang University of Science and Technology, 790-784 Pohang, Korea;(3) Center for Advanced Aerospace Materials and Department of Materials Science and Engineering, Pohang University of Science and Technology, Korea |
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Abstract: | This study is concerned with the correlation of microstructure and abrasive and sliding wear resistance of (TiC,SiC)/Ti-6Al-4V
surface composites fabricated by high-energy electron-beam irradiation. The mixtures of TiC, SiC, Ti + SiC, or TiC+SiC powders
and CaF2 flux were deposited on a Ti-6Al-4V substrate, and then an electron beam was irradiated on these mixtures. The surface composite
layers of 1.2 to 2.1 mm in thickness were homogeneously formed without defects and contained a large amount (30 to 66 vol
pct) of hard precipitates such as TiC and Ti5Si3 in the martensitic matrix. This microstructural modification, including the formation of hard precipitates in the surface
composite layer, improved the hardness and abrasive wear resistance. Particularly in the surface composite fabricated with
TiC + SiC powders, the abrasive wear resistance was greatly enhanced to a level 25 times higher than that of the Ti alloy
substrate because of the precipitation of 66 vol pct of TiC and Ti5Si3 in the hardened martensitic matrix. During the sliding wear process, hard and coarse TiC and Ti5Si3 precipitates fell off from the matrix, and their wear debris worked as abrasive particles, thereby reducing the sliding wear
resistance. On the other hand, needle-shaped Ti5Si3 particles, which did not play a significant role in enhancing abrasive wear resistance, lowered the friction coefficient
and, accordingly, decelerated the sliding wear, because they played more of the role of solid lubricants than as abrasive
particles after they fell off from the matrix. These findings indicated that high-energy electron-beam irradiation was useful
for the development of Ti-based surface composites with improved abrasive and sliding wear resistance, although the abrasive
and sliding-wear data should be interpreted by different wear mechanisms. |
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