Vacuum are remelting and electroslag remelting processes are used to p
roduce large (five tonne) insets of nickel-based superalloys, titanium
alloys, and other high-value-added alloys. The remelting processes pr
ovide controlled solidification conditions capable of producing extrem
ely uniform chemistry and microstructure; however, the con sequences o
f a single defect are potentially so great, that process improvements
are being vigorously pursued by the Specialty Metals Processing Consor
tium. The ultimate modelling goal is the realistic description of the
liquid-solid mixed-phase region of the ingot (''mushy zone''), so that
solidification defects such as freckles, macrosegregation, and solidi
fication white spots can be avoided. Reaching this goal requires a num
erical strategy capable of yielding not only accurate temperatures at
the macroscale, but also accurate temperature gradients. The numerical
procedure also requires thermophysical-property data for the alloy an
d some furnace data (such as contact resistance at ingot-crucible inte
rfaces) as well as characterization of the heat sources.