Microsegregation and secondary phase formation during directional solidification of the single-crystal Ni based superalloy LEK94
I. Lopez-Galilea, S. Huth, S. G. Fries, N. Warnken, I. Steinbach, W. Theisen.
Metallurgical and Materials Transactions A, 43, 5153–5164, (2012)
A multicomponent phase-ﬁeld method coupled to thermodynamic calculations according to the CALPHAD method was used to simulate microstructural evolution during directional solidi- ﬁcation of the LEK94 commercial single-crystal Ni-based superalloy using a two-dimensional unit cell approximation. We demonstrate quantitative agreement of calculated microsegregation proﬁles and proﬁles determined from casting experiments as well as calculated fraction solid curves with those determined in differential thermal analysis (DTA) measurements. Finally, the role of solidiﬁcation rate on dendrite morphology and precipitation of the secondary phases is investigated and a new measure of the dendrite morphology is presented to quantify the effect of back diffusion on the amount of secondary phases.