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Effect Of Crucible Diameter Reduction On The Convection, Macrosegregation, And Dendritic Morphology During Directional Solidification Of Pb-2.2 Wt Pct Sb Alloy, Jun Chen, Surendra N. Tewari, G. Magadi, H. C. Degroh Iii
Effect Of Crucible Diameter Reduction On The Convection, Macrosegregation, And Dendritic Morphology During Directional Solidification Of Pb-2.2 Wt Pct Sb Alloy, Jun Chen, Surendra N. Tewari, G. Magadi, H. C. Degroh Iii
Chemical & Biomedical Engineering Faculty Publications
The Pb-2.2 wt pct Sb alloy has been directionally solidified in 1, 2-, 3-, and 7-mm-diameter crucibles with planar and dendritic liquid-solid interface morphology. For plane front solidification, the experimentally observed macrosegregation along the solidified length follows the relationship proposed by Favier.([17,18]) Application of a 0.4 T transverse magnetic field has no effect on the extent of convection. Reducing the ampoule diameter appears to decrease the extent of convection. However, extensive convection is still present even in the 1-mm-diameter crucible. An extrapolation of the observed behavior indicates that nearly diffusive transport conditions require ampoules that are about 40 mum in …
A Mushy-Zone Rayleigh Number To Describe Interdendritic Convection During Directional Solidification Of Hypoeutectic Pb-Sb And Pb-Sn Alloys, Surendra N. Tewari, R. Tiwari
A Mushy-Zone Rayleigh Number To Describe Interdendritic Convection During Directional Solidification Of Hypoeutectic Pb-Sb And Pb-Sn Alloys, Surendra N. Tewari, R. Tiwari
Chemical & Biomedical Engineering Faculty Publications
Based on measurements of the specific dendrite surface area (S-nu), fraction of interdendritic liquid (phi), and primary dendrite spacing (lambda(1)) on transverse sections in a range of directionally solidified hypoeutectic Pb-Sb and Pb-Sn alloys that were grown at thermal gradients varying from 10 to 197 K cm(-1) and growth speeds ranging from 2 to 157 mum s(-1), it is observed that S-nu = lambda(1)(-1) S*(-0.33) (3.38 - 3.29 phi + 8.85 phi(2)), where S* = D-l G(eff)/V m(1) C-o (k - 1)/k, with D-l being the solutal diffusivity in the melt, G(eff) being the effective thermal gradient, V being the …