Microsegregation Induced Inhomogeneity of Coarsening of γ ’ Precipitates in a Nickel-based Single Crystal Superalloy

Abstract. Microsegregation induced inhomogeneity of the coarsening of cuboidal γ’(Ni3(Al,Ti)) precipitates was studied in a single crystal nickel-based superalloy CMSX-4 at temperatures ranging from 850 to 1000 °C and for an ageing time up to 5000 h. Experimental results showed a significant statistical difference in the size of the γ ’ precipitates between the dendrites and interdendritic region. The achieved results are analyzed and discussed from the point of chemical heterogeneity, activation energy for coarsening, time exponent, effective diffusion coefficient and γ/γ ’ interfacial energy which control coarsening kinetics of the cuboidal γ ’ precipitates within the dendrites and interdendritic region