An atom-probe tomographic study of freckle formation in a nickel-based superalloy

Y. Amouyal; D. N. Seidman

doi:10.1016/j.actamat.2011.07.030

An atom-probe tomographic study of freckle formation in a nickel-based superalloy

Y. Amouyal, D. N. Seidman^*

^*Corresponding author for this work

Materials Science and Engineering

Research output: Contribution to journal › Article › peer-review

35 Scopus citations

Abstract

Freckles are misoriented defects formed during the solidification of single-crystal (SC) nickel-based superalloys, which are used for turbine blades in jet engines and power generators. Freckles can cause degradation in a turbine blade's mechanical properties at high temperatures, and their elimination is of prime technological importance. Employing atom-probe tomography (APT), analytical transmission electron microscopy and dual-beam focused ion-beam microscopy, the chemical compositions of dendritic cores and inter-dendritic regions for both the freckles and the base material in a multicomponent Ni-based alloy are analyzed. The densities of four liquid-compounds with the same compositions measured using APT are calculated, and it is demonstrated that the inter-dendritic liquids have considerably smaller densities than liquids with compositions the same as the dendritic cores. The latter serves as a quantitative measure for the likelihood of freckle formation.

Original language	English (US)
Pages (from-to)	6729-6742
Number of pages	14
Journal	Acta Materialia
Volume	59
Issue number	17
DOIs	https://doi.org/10.1016/j.actamat.2011.07.030
State	Published - Oct 2011

Funding

This research was implemented in support of MEANS II AFOSR Grant No. FA9550-05-1-0089. Y.A. wishes to acknowledge the Marie Curie IOF support under the 7th framework program (FP-7) of the commission of the European Community (CEC). Dr. Larry Graham (PCC Airfoils), Prof. Tresa Pollock (University of California, Santa Barbara) and Dr. Jonathan Madison (University of Michigan, Ann Arbor) are kindly thanked for supplying alloys. Atom-probe tomographic measurements were performed in the Northwestern University Center for Atom-Probe Tomography (NUCAPT). The LEAP tomograph was purchased and upgraded with funding from NSF-MRI (DMR-0420532) and ONR-DURIP (N00014-0400798, N00014-0610539, N00014-0910781) grants. SEM and TEM analyses were performed at the Northwestern University Atomic and Nanoscale Characterization Experimental Center (NUANCE). The authors thank Dr. D. Isheim for managing NUCAPT and for helpful discussions. Prof. Sammy Tin (Illinois Institute of Technology, Chicago), Dr. Jinsong Wu and Mr. Ben Myers (NUANCE) are also kindly acknowledged for helpful discussions.

Keywords

Atom-probe tomography
Directional solidification
Freckles
Nickel-based superalloys

ASJC Scopus subject areas

Electronic, Optical and Magnetic Materials
Ceramics and Composites
Polymers and Plastics
Metals and Alloys

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10.1016/j.actamat.2011.07.030

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title = "An atom-probe tomographic study of freckle formation in a nickel-based superalloy",

abstract = "Freckles are misoriented defects formed during the solidification of single-crystal (SC) nickel-based superalloys, which are used for turbine blades in jet engines and power generators. Freckles can cause degradation in a turbine blade's mechanical properties at high temperatures, and their elimination is of prime technological importance. Employing atom-probe tomography (APT), analytical transmission electron microscopy and dual-beam focused ion-beam microscopy, the chemical compositions of dendritic cores and inter-dendritic regions for both the freckles and the base material in a multicomponent Ni-based alloy are analyzed. The densities of four liquid-compounds with the same compositions measured using APT are calculated, and it is demonstrated that the inter-dendritic liquids have considerably smaller densities than liquids with compositions the same as the dendritic cores. The latter serves as a quantitative measure for the likelihood of freckle formation.",

keywords = "Atom-probe tomography, Directional solidification, Freckles, Nickel-based superalloys",

author = "Y. Amouyal and Seidman, {D. N.}",

note = "Funding Information: This research was implemented in support of MEANS II AFOSR Grant No. FA9550-05-1-0089. Y.A. wishes to acknowledge the Marie Curie IOF support under the 7th framework program (FP-7) of the commission of the European Community (CEC). Dr. Larry Graham (PCC Airfoils), Prof. Tresa Pollock (University of California, Santa Barbara) and Dr. Jonathan Madison (University of Michigan, Ann Arbor) are kindly thanked for supplying alloys. Atom-probe tomographic measurements were performed in the Northwestern University Center for Atom-Probe Tomography (NUCAPT). The LEAP tomograph was purchased and upgraded with funding from NSF-MRI (DMR-0420532) and ONR-DURIP (N00014-0400798, N00014-0610539, N00014-0910781) grants. SEM and TEM analyses were performed at the Northwestern University Atomic and Nanoscale Characterization Experimental Center (NUANCE). The authors thank Dr. D. Isheim for managing NUCAPT and for helpful discussions. Prof. Sammy Tin (Illinois Institute of Technology, Chicago), Dr. Jinsong Wu and Mr. Ben Myers (NUANCE) are also kindly acknowledged for helpful discussions. Copyright: Copyright 2011 Elsevier B.V., All rights reserved.",

year = "2011",

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N2 - Freckles are misoriented defects formed during the solidification of single-crystal (SC) nickel-based superalloys, which are used for turbine blades in jet engines and power generators. Freckles can cause degradation in a turbine blade's mechanical properties at high temperatures, and their elimination is of prime technological importance. Employing atom-probe tomography (APT), analytical transmission electron microscopy and dual-beam focused ion-beam microscopy, the chemical compositions of dendritic cores and inter-dendritic regions for both the freckles and the base material in a multicomponent Ni-based alloy are analyzed. The densities of four liquid-compounds with the same compositions measured using APT are calculated, and it is demonstrated that the inter-dendritic liquids have considerably smaller densities than liquids with compositions the same as the dendritic cores. The latter serves as a quantitative measure for the likelihood of freckle formation.

AB - Freckles are misoriented defects formed during the solidification of single-crystal (SC) nickel-based superalloys, which are used for turbine blades in jet engines and power generators. Freckles can cause degradation in a turbine blade's mechanical properties at high temperatures, and their elimination is of prime technological importance. Employing atom-probe tomography (APT), analytical transmission electron microscopy and dual-beam focused ion-beam microscopy, the chemical compositions of dendritic cores and inter-dendritic regions for both the freckles and the base material in a multicomponent Ni-based alloy are analyzed. The densities of four liquid-compounds with the same compositions measured using APT are calculated, and it is demonstrated that the inter-dendritic liquids have considerably smaller densities than liquids with compositions the same as the dendritic cores. The latter serves as a quantitative measure for the likelihood of freckle formation.

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An atom-probe tomographic study of freckle formation in a nickel-based superalloy

Abstract

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Keywords

ASJC Scopus subject areas

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