QUANTIFICATION OF LIQUID FRACTION EVOLUTION DURING CASTING OF NI-BASE SUPERALLOYS WITH EMPHASIS ON LAST STAGE SOLIDIFICATION

摘要

An enthalpy-based method was used to calculate the evolution of fraction solid in the Ni-base superalloy, IN713LC. In the calculation, the enthalpy change was treated as a function of both temperature as well as composition. The latter was accomplished by detailed compositional measurements and use of a multi-component phase diagram database, JMatPro™ to determine the latent heat of the segregated liquid. The calculated liquid fraction incorporating micro-segregation was compared with that derived using a constant latent heat approach. It is concluded that the role of micro-segregation is important in calculating the fraction solid, in particular at the last stages of solidification. The validity of the method and the approximations used are discussed.