• 한국재료학회지
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• 제23권11호
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• pp.620-624
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• 2013

Nanocrystalline materials have recently received significant attention in the area of advanced materials engineering due to their improved physical and mechanical properties. A solid-solution nanocrystalline powder, (Ti,Mo)C, was prepared via high-energy milling of Ti-Mo alloys with graphite. Using XRD data, the synthesis process was investigated in terms of the phase evolution. Rapid sintering of nanostuctured (Ti,Mo)C hard materials was performed using a pulsed current activated sintering process (PCAS). This process allows quick densification to near theoretical density and inhibits grain growth. A dense, nanostructured (Ti,Mo)C hard material with a relative density of up to 96 % was produced by simultaneous application of 80 MPa and a pulsed current for 2 min. The average grain size of the (Ti,Mo)C was lower than 150 nm. The hardness and fracture toughness of the dense (Ti,Mo)C produced by PCAS were also evaluated. The fracture toughness of the (Ti,Mo)C was higher than that of TiC.

• 대한금속재료학회지
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• 제47권8호
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• pp.508-515
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• 2009

Ti-6Al-4V biomaterial is widely used as a bone alternative. However, Ti-6Al-4V ELI alloy suffers from numerous problems such as a high elastic modulus and high toxicity. Therefore, non-toxic biomaterials with low elastic moduli need to be developed. Ti-HA(hydroxyapatite) composites were fabricated in the present work by pulsed current activated sintering (PCAS) at $1000^{\circ}C$ under 60 MPa using mixed Ti and HA powders. The effects of HA content on the physical and mechanical properties of the sintered Ti-HA composites have been investigated. X-ray diffraction(XRD) analysis of the Ti-HA composites, including Ti-40 wt%HA in particular, revealed new phases, $Ti_{2}O$, CaO, $CaTiO_3$, and TixPy, formed by chemical reactions between Ti and HA during sintering. The hardness of the Ti-HA composites decreased with an increase in HA content. The corrosion resistance of these composites was observed to be an excellent candidate as a commercial Ti-6Al-4 V ELI alloy. A Ti-5 wt%HA composite fabricated by PCAS is recommended as a new biomaterial, because it offers good corrosion resistance, compressive strength, wear resistance, and biocompatibility, and a low Young's modulus.

• 대한금속재료학회지
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• 제49권5호
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• pp.374-379
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• 2011

Nano-powders of $Ti_3Al$ and $2Al_2O_3$ were synthesized from $3TiO_2$ and 5Al powders by high energy ball milling. A nanocrystalline $Al_2O_3$ reinforced composite was consolidated by pulsed current activated sintering within 2 minutes from mechanochemically synthesized powders of $Al_2O_3$ and $Ti_3Al$. Nanocrystalline materials, have received much attention as advanced engineering materials due to their improved physical and mechanical properties. The relative density of the composite was 99.5%. The average obtained hardness and fracture toughness values were 1510 kg/$mm^2$ and $9\;MPa{\cdot}m^{1/2}$, respectively.

• 대한금속재료학회지
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• 제50권4호
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• pp.310-315
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• 2012

Nano-powders of 1.5TiAl and $Al_2O_3$ were synthesized from $1.5TiO_2$ and 3Al powders by high energy ball milling. Nanocrystalline $Al_2O_3$ reinforced composite was consolidated by pulsed current activated sintering within 2 minutes from mechanochemically synthesized powders of $Al_2O_3$ and 1.5TiAl. The relative density of the composite was 99.5%. The average hardness and fracture toughness values obtained were $1250kg/mm^2$ and $10MPa{\cdot}m^{1/2}$, respectively.

• Journal of Welding and Joining
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• 제30권6호
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• pp.92-97
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• 2012

Using the pulsed current activated sintering method, the WC-10wt.% Co materials were densified using a WC and Co powder. The WC-Co almost completely dense with a relative density of up to 99.5 % after the simultaneous application of a pressure of 60 MPa and an electric current for 3 minutes almost without any significant change in the grain size. The average grain size of about $0.3{\mu}m$. The hardness and fracture toughness at $1000^{\circ}C$ were about $2200kg/mm^2$ and $9.8MPa.m^{1/2}$, respectively.

• 대한금속재료학회지
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• 제56권12호
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• pp.854-860
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• 2018

In spite of the many attractive properties of (W,Ti)C, its low fracture toughness limits its wide application. To improve the fracture toughness generally a second phase is added to fabricate a nanostructured composite. In this regard, graphene was considered as the reinforcing agent of (W,Ti)C. (W,Ti)C-graphene composites that were sintered within 2 min using pulsed current activated heating under a pressure of 80 MPa. The rapid consolidation method allowed retention of the nano-scale microstructure by blocking the grain growth. The effect of graphene on the hardness and microstructure of the (W,Ti)C-graphene composite was studied using a Vickers hardness tester and FE-SEM. The grain size of (W,Ti)C was reduced remarkably by the addition of graphene. Furthermore, the hardness decreased and the fracture toughness improved with the addition of graphene.