Abstract:In order to deeply understand the formationcharacteristics of freckle defects in the process of directional solidificationof nickelbased superalloy

three major equations of fluid mechanics were usedto simulate the formation of freckles during the directional solidification ofCMSX2 superalloy based on the SIMPLE (SemiImplicit Method for Pressure LinkedEquations) algorithm The simulations in the reference were used to validate themodel The effects of geometric shape and alloy composition on the flow field

solid fraction field and solute segregation distribution during solidificationof the casting were investigated The simulations show that freckles are easilyformed in the casting with shrinkage section The Al element in the alloycomposition promotes the formation of freckles

while the Ta element plays avery good role in suppressing the formation of freckles