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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.


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Typical TEM bright-field image (a) and selected area diffraction patterns ((b) and (c)) of the EDC Ti5Si3 compact at 7.0 kJ of input energy [13].
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fig6: Typical TEM bright-field image (a) and selected area diffraction patterns ((b) and (c)) of the EDC Ti5Si3 compact at 7.0 kJ of input energy [13].

Mentions: Figure 6 shows a typical TEM bright-field image (a) and selected area diffraction patterns ((b) and (c)) of the EDC Ti5Si3 compact discharged at 7.0 kJ of input energy [13]. TEM bright-field image in Figure 6(a) presents the facet grain boundary, which is quite flat suggesting that the grain boundaries of the Ti5Si3 compound are quite stable. The diffraction peaks in Figures 6(b) and 6(c) correspond to [001] and [100] zone axis of hexagonal Ti5Si3 compound (P63/mcm), respectively. Based on the analysis of the diffraction patterns, a value of the lattice parameter for the EDC Ti5Si3 compact can be calculated as a = 7.42 Å and c = 5.17 Å, which is almost identical to the value of the lattice parameter in the standard hexagonal Ti5Si3 compound; that is, a = 7.46 Å and c = 5.15 Å [14]. This indicates that there is no compositional deviation even after the electrical discharge process. This result supports that physical breakdown of the oxide film of MAed powder occurs first in the initial stage of an electrical discharge.


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)

Typical TEM bright-field image (a) and selected area diffraction patterns ((b) and (c)) of the EDC Ti5Si3 compact at 7.0 kJ of input energy [13].
© Copyright Policy - open-access
Related In: Results  -  Collection

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

fig6: Typical TEM bright-field image (a) and selected area diffraction patterns ((b) and (c)) of the EDC Ti5Si3 compact at 7.0 kJ of input energy [13].
Mentions: Figure 6 shows a typical TEM bright-field image (a) and selected area diffraction patterns ((b) and (c)) of the EDC Ti5Si3 compact discharged at 7.0 kJ of input energy [13]. TEM bright-field image in Figure 6(a) presents the facet grain boundary, which is quite flat suggesting that the grain boundaries of the Ti5Si3 compound are quite stable. The diffraction peaks in Figures 6(b) and 6(c) correspond to [001] and [100] zone axis of hexagonal Ti5Si3 compound (P63/mcm), respectively. Based on the analysis of the diffraction patterns, a value of the lattice parameter for the EDC Ti5Si3 compact can be calculated as a = 7.42 Å and c = 5.17 Å, which is almost identical to the value of the lattice parameter in the standard hexagonal Ti5Si3 compound; that is, a = 7.46 Å and c = 5.15 Å [14]. This indicates that there is no compositional deviation even after the electrical discharge process. This result supports that physical breakdown of the oxide film of MAed powder occurs first in the initial stage of an electrical discharge.

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