Determination of solute site occupancies within γ' precipitates in nickel-base superalloys via orientation-specific atom probe tomography

S. Meher; T. Rojhirunsakool; P. Nandwana; J. Tiley; R. Banerjee

doi:10.1016/j.ultramic.2015.04.015

Determination of solute site occupancies within γ' precipitates in nickel-base superalloys via orientation-specific atom probe tomography

S. Meher, T. Rojhirunsakool, P. Nandwana, J. Tiley, R. Banerjee

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

17 Scopus citations

Abstract

The analytical limitations in atom probe tomography such as resolving a desired set of atomic planes, for solving complex materials science problems, have been overcome by employing a well-developed unique and reproducible crystallographic technique, involving synergetic coupling of orientation microscopy with atom probe tomography. The crystallographic information in atom probe reconstructions has been utilized to determine the solute site occupancies in Ni-Al-Cr based superalloys accurately. The structural information in atom probe reveals that both Al and Cr occupy the same sub-lattice within the L1₂-ordered γ' precipitates to form Ni₃(Al,Cr) precipitates in a Ni-14Al-7Cr (at%) alloy. Interestingly, the addition of Co, which is a solid solution strengthener, to a Ni-14Al-7Cr alloy results in the partial reversal of Al site occupancy within γ' precipitates to form (Ni,Al)₃(Al,Cr,Co) precipitates. This unique evidence of reversal of Al site occupancy, resulting from the introduction of other solutes within the ordered structures, gives insights into the relative energetics of different sub-lattice sites when occupied by different solutes.

Original language	English
Pages (from-to)	272-277
Number of pages	6
Journal	Ultramicroscopy
Volume	159
DOIs	https://doi.org/10.1016/j.ultramic.2015.04.015
State	Published - Dec 1 2015
Externally published	Yes

Funding

The authors would like to acknowledge the U.S. Air Force Research Laboratory (AFRL Contract FA8650-08-C-5226 ) for providing financial support for this study. In addition, the authors also gratefully acknowledge the Center for Advanced Research and Technology (CART) at the University of North Texas for providing access to the experimental facilities used for this study.

Funders	Funder number
Air Force Research Laboratory	FA8650-08-C-5226

Keywords

APT
EBSD
Nickel-base superalloys
SDM
Site occupancy

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10.1016/j.ultramic.2015.04.015

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title = "Determination of solute site occupancies within γ' precipitates in nickel-base superalloys via orientation-specific atom probe tomography",

abstract = "The analytical limitations in atom probe tomography such as resolving a desired set of atomic planes, for solving complex materials science problems, have been overcome by employing a well-developed unique and reproducible crystallographic technique, involving synergetic coupling of orientation microscopy with atom probe tomography. The crystallographic information in atom probe reconstructions has been utilized to determine the solute site occupancies in Ni-Al-Cr based superalloys accurately. The structural information in atom probe reveals that both Al and Cr occupy the same sub-lattice within the L12-ordered γ' precipitates to form Ni3(Al,Cr) precipitates in a Ni-14Al-7Cr (at%) alloy. Interestingly, the addition of Co, which is a solid solution strengthener, to a Ni-14Al-7Cr alloy results in the partial reversal of Al site occupancy within γ' precipitates to form (Ni,Al)3(Al,Cr,Co) precipitates. This unique evidence of reversal of Al site occupancy, resulting from the introduction of other solutes within the ordered structures, gives insights into the relative energetics of different sub-lattice sites when occupied by different solutes.",

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AU - Meher, S.

AU - Rojhirunsakool, T.

AU - Nandwana, P.

AU - Tiley, J.

AU - Banerjee, R.

PY - 2015/12/1

Y1 - 2015/12/1

N2 - The analytical limitations in atom probe tomography such as resolving a desired set of atomic planes, for solving complex materials science problems, have been overcome by employing a well-developed unique and reproducible crystallographic technique, involving synergetic coupling of orientation microscopy with atom probe tomography. The crystallographic information in atom probe reconstructions has been utilized to determine the solute site occupancies in Ni-Al-Cr based superalloys accurately. The structural information in atom probe reveals that both Al and Cr occupy the same sub-lattice within the L12-ordered γ' precipitates to form Ni3(Al,Cr) precipitates in a Ni-14Al-7Cr (at%) alloy. Interestingly, the addition of Co, which is a solid solution strengthener, to a Ni-14Al-7Cr alloy results in the partial reversal of Al site occupancy within γ' precipitates to form (Ni,Al)3(Al,Cr,Co) precipitates. This unique evidence of reversal of Al site occupancy, resulting from the introduction of other solutes within the ordered structures, gives insights into the relative energetics of different sub-lattice sites when occupied by different solutes.

AB - The analytical limitations in atom probe tomography such as resolving a desired set of atomic planes, for solving complex materials science problems, have been overcome by employing a well-developed unique and reproducible crystallographic technique, involving synergetic coupling of orientation microscopy with atom probe tomography. The crystallographic information in atom probe reconstructions has been utilized to determine the solute site occupancies in Ni-Al-Cr based superalloys accurately. The structural information in atom probe reveals that both Al and Cr occupy the same sub-lattice within the L12-ordered γ' precipitates to form Ni3(Al,Cr) precipitates in a Ni-14Al-7Cr (at%) alloy. Interestingly, the addition of Co, which is a solid solution strengthener, to a Ni-14Al-7Cr alloy results in the partial reversal of Al site occupancy within γ' precipitates to form (Ni,Al)3(Al,Cr,Co) precipitates. This unique evidence of reversal of Al site occupancy, resulting from the introduction of other solutes within the ordered structures, gives insights into the relative energetics of different sub-lattice sites when occupied by different solutes.

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KW - Site occupancy

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Determination of solute site occupancies within γ' precipitates in nickel-base superalloys via orientation-specific atom probe tomography

Abstract

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Keywords

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