TY - JOUR
T1 - An atom-probe tomographic study of freckle formation in a nickel-based superalloy
AU - Amouyal, Y.
AU - Seidman, D. N.
N1 - 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.
PY - 2011/10
Y1 - 2011/10
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.
KW - Atom-probe tomography
KW - Directional solidification
KW - Freckles
KW - Nickel-based superalloys
UR - http://www.scopus.com/inward/record.url?scp=81155160936&partnerID=8YFLogxK
U2 - 10.1016/j.actamat.2011.07.030
DO - 10.1016/j.actamat.2011.07.030
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AN - SCOPUS:81155160936
SN - 1359-6454
VL - 59
SP - 6729
EP - 6742
JO - Acta Materialia
JF - Acta Materialia
IS - 17
ER -