On the Solidification of Metal Alloys during Microgravity Conditions

Solidification of metal alloys by rapid quenching can result in the formation of amorphous or microcrystalline solids, or materials with improved microstructural homogeneity, all with the view of forming new phases or obtaining improved properties. Some alloys may be cooled at high rates to achieve “microcrystallinity” but cannot be cooled rapidly enough to become amorphous. Other alloys may achieve both conditions depending on the cooling rate. We have examined the effects of cooling rate on the structure of one alloy that can, depending on the cooling rate, be made partially or completely amorphous. The alloy is Fe75Si15B10 (atom percent) which was formed as ribbon by melt spinning and as powder by spark erosion in dielectrics of different cooling characteristics and by gas-water atomization. The structural characteristics were determined by x-ray diffraction, measurements of magnetic properties and by optical and scanning electron microscopy.

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The Effect of The Natural Convection on The Transition from Columnar to Equiaxed Crystals:

MRS Proceedings ◽

10.1557/proc-9-619 ◽

1981 ◽

Vol 9 ◽

Author(s):

Hasse Fredriksson

Keyword(s):

Heat Transfer ◽

Natural Convection ◽

Solidification Front ◽

Growth Process ◽

Solidification Process ◽

Temperature Gradients ◽

Metal Alloys ◽

Dendritic Solidification ◽

Kinetics Of ◽

Solidification Of Metal

ABSTRACTDuring dendritic solidification of metal alloys there normally occur temperature gradients in the liquid ahead of the solidification front. The gradient causes a natural convection ahead of the front. The natural convection causes a heat transfer from the interior of the liquid, which gives the possibility for crystals to grow ahead of the solidification front. The growth of these crystals is determined by the cooling rate and the kinetics of the solidification process. The paper will deal with the theory behind the growth of free crystals ahead of a solidification front. Some experimental results will be given. The effect of gravity on the growth process will. be discussed.

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The impact of turbulent flow on the solidification of metal alloys driven by a rotating magnetic field

International Journal of Cast Metals Research ◽

10.1179/136404609x367821 ◽

2009 ◽

Vol 22 (1-4) ◽

pp. 236-239 ◽

Cited By ~ 3

Author(s):

P. A. Nikrityuk ◽

K. Eckert ◽

S. Eckert

Keyword(s):

Magnetic Field ◽

Turbulent Flow ◽

Rotating Magnetic Field ◽

Metal Alloys ◽

The Impact ◽

Solidification Of Metal

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Specimen Preparation of Near Surface Ion Irradiated Samples

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100117820 ◽

1985 ◽

Vol 43 ◽

pp. 170-171

Author(s):

K. F. Russell ◽

L. L. Horton

Keyword(s):

Radiation Damage ◽

Heavy Ions ◽

Target Material ◽

Metal Alloys ◽

Specimen Surface ◽

Specimen Preparation ◽

Particle Accelerators ◽

Near Surface ◽

Graaff Accelerator ◽

Van De Graaff

Beams of heavy ions from particle accelerators are used to produce radiation damage in metal alloys. The damaged layer extends several microns below the surface of the specimen with the maximum damage and depth dependent upon the energy of the ions, type of ions, and target material. Using 4 MeV heavy ions from a Van de Graaff accelerator causes peak damage approximately 1 μm below the specimen surface. To study this area, it is necessary to remove a thickness of approximately 1 μm of damaged metal from the surface (referred to as “sectioning“) and to electropolish this region to electron transparency from the unirradiated surface (referred to as “backthinning“). We have developed electropolishing techniques to obtain electron transparent regions at any depth below the surface of a standard TEM disk. These techniques may be applied wherever TEM information is needed at a specific subsurface position.

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