Improvement in Tensile Property of Ti64 Composites with VGCFs Fabricated by Powder Metallurgy

概要

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Ti-6Al-4V (Ti64) composite reinforced with vapor grown carbon fibers (VGCFs) was fabricated by a powder metallurgy (P/M) route in this research. Ti64 powder was mixed with VGCFs in four compositions such as 0.1, 0.2, 0.3 and 0.4 wt%, and consolidated by spark plasma sintering (SPS), followed by a hot extrusion process. The microstructure observation was carried out by optical microscopy (OM) and scanning electron microscopy (SEM). The microstructure was changed from full lamellar to bimodal after the addition of VGCFs. Almost all VGCFs reacting with Ti and turned into Ti6C3.75 compounds. Hardness was improved by the effect of solid solution strengthening of carbon in the Ti matrix and reached the maximum value of 495.8Hv. 0.2%YS and UTS were also significantly increased after adding 0.1wt% of VGCFs, but never much improved when more VGCF content was applied. Ductility of the sample was affected by a change in microstructure when 0.1 wt% of VGCFs was added, bimodal microstructures showed higher ductility compared to full lamellar structures. The relationship between fracture morphology after tensile testing and original microstructure could also be observed. At 0.1wt% of VGCFs, a good balance between strength and ductility of Ti64/VGCFs composite can be improved simultaneously.
大阪大学接合科学研究所の論文