Solute Redistribution during Planar and Dendritic Growth of Directionally Solidified Ni-Base Superalloy CMSX-10

Abstract

The solute redistribution behavior during directional solidification of the alloy CMSX-10 with planar and dendritic solid/liquid (S/L) interfaces has been investigated by directional solidification and quenching (DSQ) technique. In particular, the elemental partitioning coefficient during the solidification of primary γ and γ/γ′ eutectic was quantitatively estimated by electron probe microanalysis (EPMA) on the sample quenched during planar growth of primary γ and γ/γ′ eutectic, respectively. The EPMA compositional profiles clearly revealed that Scheil solidification occurs during the solidification of primary γ with planar S/L interface. Based on this result, the evolution of γ/γ′ eutectic volume fraction with respect to the solidification rate in dendritic solidification regimes could be rationalized by considering the back-diffusion effect on decreasing the extent of microsegregation. The comparison of the compositional profiles of Cr in the planar grown DSQ sample and the local distribution of Cr in dendritically solidified sample indicated that the solidification of the alloy CMSX-10 completes with the formation of supersaturated γ phase after the γ/γ′ eutectic reaction.

Influence of withdrawal rate on last stage solidification path of a Mo-rich Ni3Al based single crystal superalloy

“…the solidification of IDP was also influenced by solute back diffusion. This result agrees with Liu's study (G = 250 K/cm, V = 10-500 lm/s) [30], but is different from the research on CMSX-10 (G = 138 K/cm, V = 5-100 lm/s) [33], which might be ascribed to the relatively low withdrawal rates in the literature [33]. The influence of withdrawal rate on interlamellar spacing of eutectic (k) is also shown in Fig.…”

A Comparative Study of the γ/γ′ Eutectic Evolution During the Solidification of Ni-Base Superalloys

“…Recently, Seo et al [16] showed that Scheil solidification occurs during the solidification of primary c with planar S/L interface in CMSX-10. Compared to the DS with planar S/L interface that exhibits Scheil solidification, the diffusion distance is as small as a scale of dendrite arm spacing in dendritic solidification, which may give rise to the decrease in interdendritic microsegregation by solidstate back-diffusion.…”

“…the microsegregation would be negligible depending on the diffusivity of each solute element when the cooling rate is increased up to a certain limit. [16,30,33,34] The back-diffusion effect with respect to the cooling rate in CMSX-10 and CMSX-4 can be qualitatively evaluated on the basis of c/c¢ eutectic volume fraction, because all the c¢ forming elements in both alloys were found to be segregated to liquid during the solidification of primary c (Table II). Figure 10 shows a schematic illustration of the back-diffusion effect on the formation of c/c¢ eutectic, which is based on the quasi-binary Scheil model.…”

“…Note that C l was used for the determination of k i instead of the liquid composition at the S/L interface (C Ã l ) due to the strong convectional mixing of liquid during DS. [16] Table II summarizes the EPMA compositions and the partition coefficients of solute elements. No significant difference was found in the segregation tendency of solute elements between CMSX-10 and CMSX-4.…”

Compositional Approach to Designing Fcc High-Entropy Alloys that Have an Enlarged Equiaxed Zone

“…The solid/liquid interface has planar morphology due to the slow solidification rate, 0.5 µm/s. The chemical composition at the solid/liquid interface of the DSQ specimen is comparable to the composition when solidification is begun, since the DSQ specimen was quenched in the middle of solidification [13,14]. Therefore, EPMA analysis was carried out on a cross-section of the solid/liquid interface in order to calculate the partition coefficient.…”