jeff mcfadden, nist sam coriell, nist bill mitchell, nist bruce murray, suny binghamton
DESCRIPTION
Modeling of Flow during Coupled Monotectic Growth. Jeff McFadden, NIST Sam Coriell, NIST Bill Mitchell, NIST Bruce Murray, SUNY Binghamton Barry Andrews, U. Alabama, Birmingham J. Arikawa, U. Alabama, Birmingham. NASA Physical Sciences Research Division. Rod Monotectic Growth. - PowerPoint PPT PresentationTRANSCRIPT
Jeff McFadden, NIST
Sam Coriell, NIST
Bill Mitchell, NIST
Bruce Murray, SUNY Binghamton
Barry Andrews, U. Alabama, Birmingham
J. Arikawa, U. Alabama, Birmingham
Modeling of Flow during Coupled Monotectic Growth
NASA Physical Sciences Research Division
Lamellar Eutectic Growth Rod Monotectic Growth
Want better prediction of lamella and rod spacings (monotectics)
Al-In [Grugel & Hellawell (1981)]
[Hunt & Lu (1994)]
L1 Flow
Monotectic Flow Models
L2 S
Inter-rod Spacing
L1
z
r
Basic Domain
r
z
L1
Marangoni Flow
r
z
L2 S L2 S
U ~ VUm>> V
Circular Cap Model
Density Change
Jackson-Hunt Theory (1966)
Analytical Model:
Seetharaman and Trevedi (1988)
(But the predicted spacing is 4 to 5 times too small for some monotectics)
Density-Change Flow
Modified Jackson-Hunt Theory
Magnin & Trivedi [Acta Met. (1991)], Coriell et al. [JCG (1997)]
[Still separable, but no lateral transport…]
Inclusion of Lateral Transport
Stokes Flow (Sn-Pb)
Tangential Velocity Component (Sn-Pb)
Eutectic Lamellar Spacing (Sn-Pb)
Num
MJH
JH
(Predicted spacing consistent with experiment)
Euctectic Lamellar Spacing (Fe-C)
Num
MJH
JH
(Predicted spacing is 5 X too small)
Interface Concentration (Fe-C)
Modified Jackson-Hunt
Numerical
Monotectic Rod Spacing (Al-In)
JH
MJH
Num
(Predicted spacing is 4 X too small)
Rod Growth (Al-In)
Monotectic composition
Monotectic composition + 2.0 mass%
SummaryRelative to the Modified Jackson-Hunt theory:
•Lateral flow increases spacing for Sn-Pb, Al-In (augments diffusion)•Lateral flow decreases spacing for Fe-C (opposes diffusion)
Predicted spacings are still too small for monotectics
Current Work
Linear stability of a planar fluid-fluid phase boundary
in directional solidification (monotectic L1 – L2 transition)
Account for bouyancy, density change, Marangoni flow• Laplace-Young equation
•Gibbs-Thomson equation
•Classius-Clapyron equation