Effect of gravity on three-dimensional coordination number distribution in liquid phase sintered microstructures

Gravity affects microstructural evolution when a liquid phase is present during sintering. The effect of gravity on the three-dimensional coordination number distribution of tungsten grains in liquid phase sintered heavy alloy specimens is quantitatively characterized. A combination of montage seria...

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Veröffentlicht in:Acta materialia 1999-10, Vol.47 (13), p.3721-3734
Hauptverfasser: Tewari, A., Gokhale, A.M., German, R.M.
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Sprache:eng
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Zusammenfassung:Gravity affects microstructural evolution when a liquid phase is present during sintering. The effect of gravity on the three-dimensional coordination number distribution of tungsten grains in liquid phase sintered heavy alloy specimens is quantitatively characterized. A combination of montage serial sectioning, digital image processing, and unbiased stereological sampling procedures is used to estimate the coordination number distribution in three-dimensional microstructures. The microgravity environment decreases the mean coordination number. However, hardly any isolated grains are observed in the specimens, liquid phase sintered in a microgravity environment. The effect of microgravity on the coordination numbers mainly resides in its effect on the mean coordination number. In all specimens, there is a strong correlation between grain size and coordination number, which can be expressed as [D c / D ̄ ] 2=C/C 0 where C 0 is the mean coordination number, D̄ the global average size of the tungsten grains, and D c the average size of only those grains which have coordination number C.
ISSN:1359-6454
1873-2453
DOI:10.1016/S1359-6454(99)00164-0