A freckle criterion for the solidification of superalloys with a tilted solidification front

• DOI: 10.1007/s11837-004-0202-7
• Publication Date: 2007-06-22T05:13:01Z
• Authors: Wan-Hong Yang; John J. deBarbadillo; Koki Morita; T. Suzuki; Wei Chen; Keh-Minn Chang
• Keywords: Directional solidification; Dendrite (mathematics)

A freckle criterion developed from M.C. Fleming’s macrosegregation theory was extended to consider the effect of the slope of the solidification front. Such slopes are always associated with the remelting of alloy ingots and are frequently encountered in the directional solidification of single crystal and directionally solidified blades. When experimental verification of the criterion was carried out using the horizontal directional solidification method, dendrite growth rate was found to be a key factor in the formation of freckles. The criterion derived considering the slope of the solidification front describes the occurrence of freckles relatively well. Critical values for freckle formation were obtained for a few nickel-base superalloys.