Solidification structure control by magnetic fields

The effect of DC and AC magnetic fields on the macrostructure, morphology and distribution of the iron-containing intermetallics in the commercially pure Al was investigated. It is found that, at a cooling rate of 3°C/min, the grain is very coarse when the alloy solidifies both with and without magnetic fields. Comparing with the sample solidifies without magnetic field, the solidification structure has almost no change when it solidifies under DC magnetic field, while AC magnetic field changes the solidification structure obviously and makes grains show radial columnar crystals. The intermetallics is dominated by long needle-like phase when the sample solidifies under the condition of no magnetic field. Under AC magnetic field, the intermetallics is refined and accumulated towards the center of sample, and the amount of bone-like α-AlFeSi phase is increased remarkably. The mechanism of the effect of magnetic fields was discussed.

Download Full-text

Solidification and Solidification Structure Control of Weld Metals.

JOURNAL OF THE JAPAN WELDING SOCIETY ◽

10.2207/qjjws1943.70.5_579 ◽

2001 ◽

Vol 70 (5) ◽

pp. 579-595 ◽

Cited By ~ 2

Author(s):

Toshihiko KOSEKI

Keyword(s):

Solidification Structure ◽

Structure Control ◽

Weld Metals

Download Full-text

Effect of time–modulated magnetic fields on the solidification structure and extrusion properties of wrought aluminum alloys

IOP Conference Series Materials Science and Engineering ◽

10.1088/1757-899x/424/1/012039 ◽

2018 ◽

Vol 424 ◽

pp. 012039

Author(s):

D. Räbiger ◽

C. Resewski ◽

S. Müller ◽

B. Willers ◽

W. Reimers ◽

...

Keyword(s):

Aluminum Alloys ◽

Magnetic Fields ◽

Solidification Structure ◽

Wrought Aluminum Alloys ◽

Wrought Aluminum

Download Full-text

Calculated Coronal Magnetic Fields and Their Comparison with the Coronal Structures as Observed during Five Solar Eclipses

International Astronomical Union Colloquium ◽

10.1017/s0252921100026038 ◽

1994 ◽

Vol 144 ◽

pp. 559-564

Author(s):

P. Ambrož ◽

J. Sýkora

Keyword(s):

Magnetic Field ◽

Solar Cycle ◽

Magnetic Fields ◽

Solar Corona ◽

Coronal Magnetic Field ◽

Coronal Magnetic Fields ◽

Solar Eclipses ◽

Coronal Structures

AbstractWe were successful in observing the solar corona during five solar eclipses (1973-1991). For the eclipse days the coronal magnetic field was calculated by extrapolation from the photosphere. Comparison of the observed and calculated coronal structures is carried out and some peculiarities of this comparison, related to the different phases of the solar cycle, are presented.

Download Full-text

Radio Measurements of Coronal Magnetic Fields

International Astronomical Union Colloquium ◽

10.1017/s0252921100024933 ◽

1994 ◽

Vol 144 ◽

pp. 21-28 ◽

Cited By ~ 4

Author(s):

G. B. Gelfreikh

Keyword(s):

Magnetic Field ◽

Magnetic Fields ◽

Solar Corona ◽

Active Regions ◽

High Sensitivity ◽

Coronal Magnetic Field ◽

Transverse Magnetic ◽

Radio Sources ◽

Radio Waves ◽

Solar Active Regions

AbstractA review of methods of measuring magnetic fields in the solar corona using spectral-polarization observations at microwaves with high spatial resolution is presented. The methods are based on the theory of thermal bremsstrahlung, thermal cyclotron emission, propagation of radio waves in quasi-transverse magnetic field and Faraday rotation of the plane of polarization. The most explicit program of measurements of magnetic fields in the atmosphere of solar active regions has been carried out using radio observations performed on the large reflector radio telescope of the Russian Academy of Sciences — RATAN-600. This proved possible due to good wavelength coverage, multichannel spectrographs observations and high sensitivity to polarization of the instrument. Besides direct measurements of the strength of the magnetic fields in some cases the peculiar parameters of radio sources, such as very steep spectra and high brightness temperatures provide some information on a very complicated local structure of the coronal magnetic field. Of special interest are the results found from combined RATAN-600 and large antennas of aperture synthesis (VLA and WSRT), the latter giving more detailed information on twodimensional structure of radio sources. The bulk of the data obtained allows us to investigate themagnetospheresof the solar active regions as the space in the solar corona where the structures and physical processes are controlled both by the photospheric/underphotospheric currents and surrounding “quiet” corona.

Download Full-text