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Refinement and growth enhancement of Al2Cu phase during magnetic field assisting directional solidification of hypereutectic Al-Cu alloy.

Wang J, Yue S, Fautrelle Y, Lee PD, Li X, Zhong Y, Ren Z - Sci Rep (2016)

Bottom Line: Understanding how the magnetic fields affect the formation of reinforced phase during solidification is crucial to tailor the structure and therefor the performance of metal matrix in situ composites.With rising magnetic fields, both increase of Al2Cu phase's total volume and decrease of each column's transverse section area were found.To verify this, a real structure based 3D simulation of TEMF in Al2Cu column was carried out, and the dislocations in the Al2Cu phase obtained without and with a 10T high magnetic field were analysed by the transmission electron microscope.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Advanced Special Steel, Shanghai University, Shanghai 200072, China.

ABSTRACT
Understanding how the magnetic fields affect the formation of reinforced phase during solidification is crucial to tailor the structure and therefor the performance of metal matrix in situ composites. In this study, a hypereutectic Al-40 wt.%Cu alloy has been directionally solidified under various axial magnetic fields and the morphology of Al2Cu phase was quantified in 3D by means of high resolution synchrotron X-ray tomography. With rising magnetic fields, both increase of Al2Cu phase's total volume and decrease of each column's transverse section area were found. These results respectively indicate the growth enhancement and refinement of the primary Al2Cu phase in the magnetic field assisting directional solidification. The thermoelectric magnetic forces (TEMF) causing torque and dislocation multiplication in the faceted primary phases were thought dedicate to respectively the refinement and growth enhancement. To verify this, a real structure based 3D simulation of TEMF in Al2Cu column was carried out, and the dislocations in the Al2Cu phase obtained without and with a 10T high magnetic field were analysed by the transmission electron microscope.

No MeSH data available.


Related in: MedlinePlus

Bright field transmission electron microscope images of Al–40 wt.%Cu alloys obtained without (a) and with a 10T magnetic field (b) at the growth rate of 2 μm/s and the thermal gradient of 6000 K/m.
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f4: Bright field transmission electron microscope images of Al–40 wt.%Cu alloys obtained without (a) and with a 10T magnetic field (b) at the growth rate of 2 μm/s and the thermal gradient of 6000 K/m.

Mentions: In terms of the increase of Al2Cu phases’ total volume, which is attributed to the fasted growth rate of the faceted phases when magnetic field is presence. It is known that the faceted phase’s growth rate is dominated by the atom attachment process, and the defects in the solid, like dislocations, could provide more vacancies for the approaching atoms to easy their locating. It is therefore not difficult to get that the dislocation multiplication could fast the growth of faceted phases. It is so happen that the stressed solid is a favourite condition for the dislocation multiplication, and thus the strong stresses (up to 3.3 × 108 N/m2) caused by TEMF in the Al2Cu column are thought to be the main reason for the observed growth enhancement. To verify such interpretation, the dislocations in the solid were analysed by the transmission electron microscope. Figure 4 shows the bright field images of Al-40 wt.%Cu samples fabricated without and with a 10T magnetic field. It manifests that a number of dislocations form in the sample solidified under magnetic field and nearly dislocation free structure is obtained without the magnetic field. Moreover, it should point out that the continuous increase of Al2Cu columns’ total volume with magnetic field can be also explained by the linear proportion of TEMF to the applied magnetic fields.


Refinement and growth enhancement of Al2Cu phase during magnetic field assisting directional solidification of hypereutectic Al-Cu alloy.

Wang J, Yue S, Fautrelle Y, Lee PD, Li X, Zhong Y, Ren Z - Sci Rep (2016)

Bright field transmission electron microscope images of Al–40 wt.%Cu alloys obtained without (a) and with a 10T magnetic field (b) at the growth rate of 2 μm/s and the thermal gradient of 6000 K/m.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4835779&req=5

f4: Bright field transmission electron microscope images of Al–40 wt.%Cu alloys obtained without (a) and with a 10T magnetic field (b) at the growth rate of 2 μm/s and the thermal gradient of 6000 K/m.
Mentions: In terms of the increase of Al2Cu phases’ total volume, which is attributed to the fasted growth rate of the faceted phases when magnetic field is presence. It is known that the faceted phase’s growth rate is dominated by the atom attachment process, and the defects in the solid, like dislocations, could provide more vacancies for the approaching atoms to easy their locating. It is therefore not difficult to get that the dislocation multiplication could fast the growth of faceted phases. It is so happen that the stressed solid is a favourite condition for the dislocation multiplication, and thus the strong stresses (up to 3.3 × 108 N/m2) caused by TEMF in the Al2Cu column are thought to be the main reason for the observed growth enhancement. To verify such interpretation, the dislocations in the solid were analysed by the transmission electron microscope. Figure 4 shows the bright field images of Al-40 wt.%Cu samples fabricated without and with a 10T magnetic field. It manifests that a number of dislocations form in the sample solidified under magnetic field and nearly dislocation free structure is obtained without the magnetic field. Moreover, it should point out that the continuous increase of Al2Cu columns’ total volume with magnetic field can be also explained by the linear proportion of TEMF to the applied magnetic fields.

Bottom Line: Understanding how the magnetic fields affect the formation of reinforced phase during solidification is crucial to tailor the structure and therefor the performance of metal matrix in situ composites.With rising magnetic fields, both increase of Al2Cu phase's total volume and decrease of each column's transverse section area were found.To verify this, a real structure based 3D simulation of TEMF in Al2Cu column was carried out, and the dislocations in the Al2Cu phase obtained without and with a 10T high magnetic field were analysed by the transmission electron microscope.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Advanced Special Steel, Shanghai University, Shanghai 200072, China.

ABSTRACT
Understanding how the magnetic fields affect the formation of reinforced phase during solidification is crucial to tailor the structure and therefor the performance of metal matrix in situ composites. In this study, a hypereutectic Al-40 wt.%Cu alloy has been directionally solidified under various axial magnetic fields and the morphology of Al2Cu phase was quantified in 3D by means of high resolution synchrotron X-ray tomography. With rising magnetic fields, both increase of Al2Cu phase's total volume and decrease of each column's transverse section area were found. These results respectively indicate the growth enhancement and refinement of the primary Al2Cu phase in the magnetic field assisting directional solidification. The thermoelectric magnetic forces (TEMF) causing torque and dislocation multiplication in the faceted primary phases were thought dedicate to respectively the refinement and growth enhancement. To verify this, a real structure based 3D simulation of TEMF in Al2Cu column was carried out, and the dislocations in the Al2Cu phase obtained without and with a 10T high magnetic field were analysed by the transmission electron microscope.

No MeSH data available.


Related in: MedlinePlus