Limits...
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

Linear pinch effect with a uniform current distribution.
© Copyright Policy - open-access
Related In: Results  -  Collection


getmorefigures.php?uid=PMC4389978&req=5

fig8: Linear pinch effect with a uniform current distribution.

Mentions: When a capacitor bank is discharged through a powder column, a long cylindrical metal powder column conducting an axial current, distributed axisymmetrically as shown in Figure 8, tends to contract radially inwards. At this moment the magnetic field generated by the current flow causes a diametric contraction, which is known as the pinch effect [20]. The magnitude of the magnetic field (B) can be obtained by using (5)B=12μrj,where μ is the permeability, j is the current density, and r is the distance from the center of the powder column. The resulting pinch pressure (P) is the mechanical force acting on the powder column that will produce a solid core. The pinch pressure is given by (6)P=μj2a2−r24,where a is the radius of the cylindrical powder column. Allow the diameter (2a) of the contact region to be approximately one-tenth of the diameter of an average powder particle, as is often the case in solid mechanics [21]. MAed Ti5Si3 powder particles are considered to be stacked in such a linear manner that only one contact point is formed, resulting in the parallel straight current passage. The geometrical parameters needed for estimating the pinch pressure can be obtained and are tabulated in Table 4. Using these parameters, the maximum pinch pressure can be estimated in the center of the contact area (at r = 0). The resulting pinch pressures calculated under current experimental conditions are also listed in Table 3. It can be known that the pinch pressures between 300 and 322 MPa by the discharge were generated and could pressurize the liquidus powder particles, producing a bulk-typed Ti5Si3 compact without containing pores.


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)

Linear pinch effect with a uniform current distribution.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

fig8: Linear pinch effect with a uniform current distribution.
Mentions: When a capacitor bank is discharged through a powder column, a long cylindrical metal powder column conducting an axial current, distributed axisymmetrically as shown in Figure 8, tends to contract radially inwards. At this moment the magnetic field generated by the current flow causes a diametric contraction, which is known as the pinch effect [20]. The magnitude of the magnetic field (B) can be obtained by using (5)B=12μrj,where μ is the permeability, j is the current density, and r is the distance from the center of the powder column. The resulting pinch pressure (P) is the mechanical force acting on the powder column that will produce a solid core. The pinch pressure is given by (6)P=μj2a2−r24,where a is the radius of the cylindrical powder column. Allow the diameter (2a) of the contact region to be approximately one-tenth of the diameter of an average powder particle, as is often the case in solid mechanics [21]. MAed Ti5Si3 powder particles are considered to be stacked in such a linear manner that only one contact point is formed, resulting in the parallel straight current passage. The geometrical parameters needed for estimating the pinch pressure can be obtained and are tabulated in Table 4. Using these parameters, the maximum pinch pressure can be estimated in the center of the contact area (at r = 0). The resulting pinch pressures calculated under current experimental conditions are also listed in Table 3. It can be known that the pinch pressures between 300 and 322 MPa by the discharge were generated and could pressurize the liquidus powder particles, producing a bulk-typed Ti5Si3 compact without containing pores.

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