Influence of Rhenium and Cooling Rate on the Solidification of Ni Base Superalloys, Inconel 718

El-Bagoury, Nader; Yamamoto, Kazuya; Miyahara, Hirofumi; Ōgi, Keisaku

doi:10.2320/matertrans.46.909

Cited by 9 publications

(6 citation statements)

References 14 publications

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“…The width of columnar/cellular structures increases with increasing Re content ( Figure 5) from 893 ± 223 to 1936 ± 515 nm observed for IN718 and IN718-6Re, respectively. A similar effect of Re addition was observed by El-Bagoury et al [40] for cast IN718 alloy. Higher Re content resulted in the increased volume fraction of c phase and enlarged dendrite arm spacing.…”

Section: B Microstructure Of In718-re Alloyssupporting

confidence: 86%

The Effect of Rhenium Addition on Microstructure and Corrosion Resistance of Inconel 718 Processed by Selective Laser Melting

Majchrowicz

Pakieła

Kamiński

et al. 2018

Metall Mater Trans A

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In this study, the effect of rhenium addition (2, 4, and 6 wt pct) and building orientation (0 and 90 deg) on the microstructure and corrosion resistance of Inconel 718 (IN718) alloy processed by selective laser melting (SLM) was investigated. Microstructure characterization showed that the as-built IN718-Re alloys consist of columnar grains growing parallel to the building direction (Z-axis). Each columnar grain was characterized by a fine columnar/cellular dendritic substructure with Nb-and Mo-rich Laves phases and MC-type carbides embedded in the interdendritic spaces. Rhenium addition segregated to c phase dendrites which resulted in an increase of the columnar/cellular substructures width with increasing Re content. Due to a strong microstructure anisotropy of SLM-processed IN718-Re alloys, the corrosion properties were examined for mutually perpendicular planes: XY (90 deg samples) and XZ (0 deg). The presence of rhenium enhanced the corrosion resistance of IN718 alloy in 0.1 M Na 2 SO 4 and NaCl solutions at both exposed planes. The corrosion current density was significantly reduced for IN718-Re alloys and increasing Re content correlated with a more positive shift in corrosion potential. Moreover, the XY plane possessed better corrosion resistance than the XZ plane due to the higher fraction of laser overlapping areas observed for the XZ plane.

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Section: B Microstructure Of In718-re Alloyssupporting

confidence: 86%

The Effect of Rhenium Addition on Microstructure and Corrosion Resistance of Inconel 718 Processed by Selective Laser Melting

Majchrowicz

Pakieła

Kamiński

et al. 2018

Metall Mater Trans A

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“…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.…”

Section: Effect Of Back-diffusion and Dendrite Arm Coarseningmentioning

confidence: 99%

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

Seo

Lee

Yoo

et al. 2011

Metall Mater Trans A

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The evolution of c/c¢ eutectic during the solidification of Ni-base superalloys CMSX-10 and CMSX-4 was investigated over a wide range of cooling rates. The microsegregation behavior during solidification was also quantitatively examined to clarify the influence of elemental segregation on the evolution of c/c¢ eutectic. In the cooling rate ranges investigated (0.9 to 138.4 K/min (0.9 to 138.4°C/min)), the c/c¢ eutectic fraction in CMSX-10 was found to be more than 2 times higher than that in CMSX-4 at a given cooling rate. However, the dependence of the c/c¢ eutectic fraction on the cooling rate in both alloys showed a similar tendency; i.e., the c/c¢ eutectic fraction increased with increasing the cooling rate and then exhibited a maximum plateau at and above the certain critical cooling rate in both alloys. This critical cooling rate was found to be dependent on the alloy composition and was estimated to be about 12 K/min (12°C/min) and 25 K/min (25°C/min) for CMSX-10 and CMSX-4, respectively. The calculated solid compositions based on the modified Scheil model revealed that even a small compositional difference of total c¢ forming elements in the initial composition of the alloy can play a significant role in the as-cast eutectic fraction during the solidification of Ni-base superalloys. The evolution of the c/c¢ eutectic fraction with respect to the cooling rate could be rationalized by taking into account the effects of back-diffusion in solid and dendrite arm coarsening on decreasing the extent of microsegregation.

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“…It has been known that the extent of back-diffusion in solid during solidification is proportional to the local solidification times and the diffusivity of solute element in solid ( s ), while it is inversely proportional to the square of the diffusion distance and the cooling rate ( [26]. Regarding the influence of the cooling rate on the extent of back-diffusion, El-Bagoury et al [27] have recently shown that the microsegregation of Nb between the dendrite core and interdendritic region decreases at lower cooling rate of about 1.0 K/min by back-diffusion in alloy IN718. However, they have Table III.…”

Section: Effect Of Back-diffusion During Dendritic Solidificationmentioning

confidence: 99%

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

Seo

Lee

Yoo

et al. 2008

Superalloys 2008 (Eleventh International Symposium)

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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.

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Influence of Rhenium and Cooling Rate on the Solidification of Ni Base Superalloys, Inconel 718

Cited by 9 publications

References 14 publications

The Effect of Rhenium Addition on Microstructure and Corrosion Resistance of Inconel 718 Processed by Selective Laser Melting

The Effect of Rhenium Addition on Microstructure and Corrosion Resistance of Inconel 718 Processed by Selective Laser Melting

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

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

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