Abstract
The multiphase model developed in part I for equiaxed dendritic solidification with melt convection and solid-phase transport is applied to numerically predict structural and compositional development in an Al-4 wt pct Cu alloy solidifying in a rectangular cavity. A numerical technique combining a fully implicit control-volume-based finite difference method with a multiple time-step scheme is developed for accurate and efficient simulations of both micro- and macroscale phenomena. Quantitative results for the dendritic microstructure evolution in the presence of melt convection and solid movement are obtained. The remarkable effects of the solid-liquid multiphase flow pattern on macrosegregation as well as the grain size distribution are illustrated.
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Abbreviations
- C :
-
concentration of a chemical species, wt pct
- c :
-
specific heat, J/kg K
- C ∃ :
-
settling ratio
- d e :
-
mean characteristic diameter of the dendrite envelope, m
- D :
-
mass diffusion coefficient, m2/s
- h :
-
chill heat-transfer coefficient (W/m2 K) or enthalpy (J/kg)
- Iv:
-
Ivantsov function
- k :
-
thermal conductivity, W/m K
- l :
-
species diffusion length, m
- m l :
-
liquidus line slope, K/wt pct
- Ms d :
-
solid/liquid interfacial drag, N/m s
- n :
-
equiaxed nuclei density, m-3
- n :
-
outwardly directed unit normal vector
- Pe∃ :
-
multiphase Pelcet number, ⃛l|vl -v s|de/Dl
- Pet :
-
solutal Peclet number at the dendrite tip,-V tRt/2Dl
- Pe∞:
-
ambient Pelcet number for dendrite tips, |vl -
- R t :
-
tip radius, m
- S :
-
interfacial area concentration, m-1
- t :
-
time, s
- T :
-
temperature, K
- T :
-
cooling rate,∂T/∂t (K/s)
- v:
-
velocity vector, m/s
- w :
-
interface velocity, m/s
- β :
-
dimensionless parameter
- γ :
-
momentum dispersion coefficient
- γ:
-
interfacial phase change rate (kg/m3 s) or Gibbs-Thomson coefficient (m K)
- δh :
-
latent heat of phase change, J/kg
- ⃛:
-
volume fraction
- ⃛ si :
-
internal solid fraction, ⃛s/(⃛ s + ⃛d)
- k :
-
partition coefficient, wt pct/wt pct
- k v :
-
flow partition coefficient
- λ 2 :
-
secondary dendrite arm spacing, m
- λ p :
-
slip coefficient for solid, m
- p :
-
density, kg/m3
- Μ :
-
viscosity, Pa s
- Σ* :
-
stability constant
- ψ :
-
a field property
- Ω :
-
solutal supersaturation,(C e- Cl)/[Ce(l-k)]
- d :
-
interdendritic liquid
- e :
-
dendrite envelope
- E :
-
eutectic point
- eff:
-
effective
- f :
-
total liquid phase(d + l)
- g :
-
grain
- k :
-
phasek
- I :
-
extradendritic liquid
- L :
-
liquidus
- Id :
-
extradendritic-interdendritic liquid interface
- m :
-
melting point of pure metals
- n :
-
normal direction
- N :
-
nucleation
- 0:
-
initial state
- s :
-
solid
- sd :
-
solid-interdendritic liquid interface
- t :
-
dendrite tip or tangential
- w :
-
wall
- c :
-
critical
- -:
-
interfacial area-averaged
- *:
-
effective
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Wang, C.Y., Beckermann, C. Equiaxed dendritic solidification with convection: Part II. Numerical simulations for an Al-4 Wt pct Cu alloy. Metall Mater Trans A 27, 2765–2783 (1996). https://doi.org/10.1007/BF02652370
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DOI: https://doi.org/10.1007/BF02652370