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Self-consolidation mechanism of nanostructured Ti5Si3 compact induced by electrical discharge.

Lee WH, Cheon YW, Jo YH, Seong JG, Jo YJ, Kim YH, Noh MS, Jeong HG, Van Tyne CJ, Chang SY - ScientificWorldJournal (2015)

Bottom Line: A solid bulk of nanostructured Ti5Si3 with no compositional deviation was obtained in times as short as 159 μsec by the discharge.Followed rapid cooling preserved the nanostructure of consolidated Ti5Si3 compact.Complete conversion yielding a single phase Ti5Si3 is primarily dominated by the solid-liquid mechanism.

View Article: PubMed Central - PubMed

Affiliation: Faculty of Nanotechnology and Advanced Materials Engineering, Sejong University, Seoul 143-747, Republic of Korea.

ABSTRACT
Electrical discharge using a capacitance of 450 μF at 7.0 and 8.0 kJ input energies was applied to mechanical alloyed Ti5Si3 powder without applying any external pressure. A solid bulk of nanostructured Ti5Si3 with no compositional deviation was obtained in times as short as 159 μsec by the discharge. During an electrical discharge, the heat generated is the required parameter possibly to melt the Ti5Si3 particles and the pinch force can pressurize the melted powder without allowing the formation of pores. Followed rapid cooling preserved the nanostructure of consolidated Ti5Si3 compact. Three stepped processes during an electrical discharge for the formation of nanostructured Ti5Si3 compact are proposed: (a) a physical breakdown of the surface oxide of Ti5Si3 powder particles, (b) melting and condensation of Ti5Si3 powder by the heat and pinch pressure, respectively, and (c) rapid cooling for the preservation of nanostructure. Complete conversion yielding a single phase Ti5Si3 is primarily dominated by the solid-liquid mechanism.

No MeSH data available.


Related in: MedlinePlus

Resistance variation of MAed Ti5Si3 powder column calculated from the voltage and current recordings during an electrical discharge.
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Related In: Results  -  Collection


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fig10: Resistance variation of MAed Ti5Si3 powder column calculated from the voltage and current recordings during an electrical discharge.

Mentions: Figure 10 shows the resistance change through the MAed Ti5Si3 powder column during an electrical discharge, which was determined from the recordings of voltage and current. It can be seen that there are three distinct regions: 0 to 6 μsec as stage 1, 7 to 146 μsec as stage 2, and 147 to 159 μsec as stage 3. In stage 1, electronic and physical breakdown of the oxide layer of MAed Ti5Si3 powder occurred, causing the rapid drop of resistance. In stage 2, the resistance decreased very slowly. The heat generated during a discharge would liquefy the MAed Ti5Si3 powder. Both condensation and densification of melted Ti5Si3 powder are promoted by the pinch force, especially in the center of the powder column. In stage 3, another rapid drop of resistance occurred. The rapid cooling occurs in this stage, resulting in the preservation of nanosized crystallite of Ti5Si3 compact.


Self-consolidation mechanism of nanostructured Ti5Si3 compact induced by electrical discharge.

Lee WH, Cheon YW, Jo YH, Seong JG, Jo YJ, Kim YH, Noh MS, Jeong HG, Van Tyne CJ, Chang SY - ScientificWorldJournal (2015)

Resistance variation of MAed Ti5Si3 powder column calculated from the voltage and current recordings during an electrical discharge.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4389978&req=5

fig10: Resistance variation of MAed Ti5Si3 powder column calculated from the voltage and current recordings during an electrical discharge.
Mentions: Figure 10 shows the resistance change through the MAed Ti5Si3 powder column during an electrical discharge, which was determined from the recordings of voltage and current. It can be seen that there are three distinct regions: 0 to 6 μsec as stage 1, 7 to 146 μsec as stage 2, and 147 to 159 μsec as stage 3. In stage 1, electronic and physical breakdown of the oxide layer of MAed Ti5Si3 powder occurred, causing the rapid drop of resistance. In stage 2, the resistance decreased very slowly. The heat generated during a discharge would liquefy the MAed Ti5Si3 powder. Both condensation and densification of melted Ti5Si3 powder are promoted by the pinch force, especially in the center of the powder column. In stage 3, another rapid drop of resistance occurred. The rapid cooling occurs in this stage, resulting in the preservation of nanosized crystallite of Ti5Si3 compact.

Bottom Line: A solid bulk of nanostructured Ti5Si3 with no compositional deviation was obtained in times as short as 159 μsec by the discharge.Followed rapid cooling preserved the nanostructure of consolidated Ti5Si3 compact.Complete conversion yielding a single phase Ti5Si3 is primarily dominated by the solid-liquid mechanism.

View Article: PubMed Central - PubMed

Affiliation: Faculty of Nanotechnology and Advanced Materials Engineering, Sejong University, Seoul 143-747, Republic of Korea.

ABSTRACT
Electrical discharge using a capacitance of 450 μF at 7.0 and 8.0 kJ input energies was applied to mechanical alloyed Ti5Si3 powder without applying any external pressure. A solid bulk of nanostructured Ti5Si3 with no compositional deviation was obtained in times as short as 159 μsec by the discharge. During an electrical discharge, the heat generated is the required parameter possibly to melt the Ti5Si3 particles and the pinch force can pressurize the melted powder without allowing the formation of pores. Followed rapid cooling preserved the nanostructure of consolidated Ti5Si3 compact. Three stepped processes during an electrical discharge for the formation of nanostructured Ti5Si3 compact are proposed: (a) a physical breakdown of the surface oxide of Ti5Si3 powder particles, (b) melting and condensation of Ti5Si3 powder by the heat and pinch pressure, respectively, and (c) rapid cooling for the preservation of nanostructure. Complete conversion yielding a single phase Ti5Si3 is primarily dominated by the solid-liquid mechanism.

No MeSH data available.


Related in: MedlinePlus