Atom probe tomographic studies of precipitation in Al-O. 1Zr-O. 1Ti (at.%) alloys

Keith E. Knipling; David C. Dunand; David N. Seidman

doi:10.1017/S1431927607070882

Atom probe tomographic studies of precipitation in Al-O. 1Zr-O. 1Ti (at.%) alloys

Keith E. Knipling^*, David C. Dunand, David N. Seidman

^*Corresponding author for this work

Materials Science and Engineering

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

23 Scopus citations

Abstract

Atom probe tomography was utilized to measure directly the chemical compositions of Al₃(Zr_1-xTi_x) precipitates with a metastable Ll₂ structure formed in Al-0. 1Zr-0.1Ti (at.%) alloys upon aging at 375°C or 425°C. The alloys exhibit an inhomogeneous distribution of Al₃(Zr_1-xTi_x) precipitates, as a result of a nonuniform dendritic distribution of solute atoms after casting. At these aging temperatures, the Zr:Ti atomic ratio in the precipitates is about 10 and 5, respectively, indicating that Ti remains mainly in solid solution rather than partitioning to the Al₃(Zr_1-xTi_x) precipitates. This is interpreted as being due to the very small diffusivity of Ti in α-Al, consistent with prior studies on Al-Sc-Ti and Al-Sc-Zr alloys, where the slower diffusing Zr and Ti atoms make up a small fraction of the Al₃(Sc_1-x/Ti_x/Zr_x) precipitates. Unlike those alloys, however, the present Al-Zr-Ti alloys exhibit no interfacial segregation of Ti at the matrix/precipitate heterophase interface, a result that may be affected by a significant disparity in the evaporation fields of the α-Al matrix and Al₃(Zr_1-xTi_x) precipitates and/or a lack of local thermodynamic equilibrium at the interface.

Original language	English (US)
Pages (from-to)	503-516
Number of pages	14
Journal	Microscopy and Microanalysis
Volume	13
Issue number	6
DOIs	https://doi.org/10.1017/S1431927607070882
State	Published - Dec 2007

Keywords

Al-Zr-Ti
AlZr precipitates
Atom probe tomography
Local magnification

ASJC Scopus subject areas

Instrumentation

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10.1017/S1431927607070882

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title = "Atom probe tomographic studies of precipitation in Al-O. 1Zr-O. 1Ti (at.%) alloys",

abstract = "Atom probe tomography was utilized to measure directly the chemical compositions of Al3(Zr1-xTix) precipitates with a metastable Ll2 structure formed in Al-0. 1Zr-0.1Ti (at.%) alloys upon aging at 375°C or 425°C. The alloys exhibit an inhomogeneous distribution of Al3(Zr1-xTix) precipitates, as a result of a nonuniform dendritic distribution of solute atoms after casting. At these aging temperatures, the Zr:Ti atomic ratio in the precipitates is about 10 and 5, respectively, indicating that Ti remains mainly in solid solution rather than partitioning to the Al3(Zr1-xTix) precipitates. This is interpreted as being due to the very small diffusivity of Ti in α-Al, consistent with prior studies on Al-Sc-Ti and Al-Sc-Zr alloys, where the slower diffusing Zr and Ti atoms make up a small fraction of the Al3(Sc1-x/Tix/Zrx) precipitates. Unlike those alloys, however, the present Al-Zr-Ti alloys exhibit no interfacial segregation of Ti at the matrix/precipitate heterophase interface, a result that may be affected by a significant disparity in the evaporation fields of the α-Al matrix and Al3(Zr1-xTix) precipitates and/or a lack of local thermodynamic equilibrium at the interface.",

keywords = "Al-Zr-Ti, AlZr precipitates, Atom probe tomography, Local magnification",

author = "Knipling, {Keith E.} and Dunand, {David C.} and Seidman, {David N.}",

year = "2007",

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AU - Knipling, Keith E.

AU - Dunand, David C.

AU - Seidman, David N.

PY - 2007/12

Y1 - 2007/12

N2 - Atom probe tomography was utilized to measure directly the chemical compositions of Al3(Zr1-xTix) precipitates with a metastable Ll2 structure formed in Al-0. 1Zr-0.1Ti (at.%) alloys upon aging at 375°C or 425°C. The alloys exhibit an inhomogeneous distribution of Al3(Zr1-xTix) precipitates, as a result of a nonuniform dendritic distribution of solute atoms after casting. At these aging temperatures, the Zr:Ti atomic ratio in the precipitates is about 10 and 5, respectively, indicating that Ti remains mainly in solid solution rather than partitioning to the Al3(Zr1-xTix) precipitates. This is interpreted as being due to the very small diffusivity of Ti in α-Al, consistent with prior studies on Al-Sc-Ti and Al-Sc-Zr alloys, where the slower diffusing Zr and Ti atoms make up a small fraction of the Al3(Sc1-x/Tix/Zrx) precipitates. Unlike those alloys, however, the present Al-Zr-Ti alloys exhibit no interfacial segregation of Ti at the matrix/precipitate heterophase interface, a result that may be affected by a significant disparity in the evaporation fields of the α-Al matrix and Al3(Zr1-xTix) precipitates and/or a lack of local thermodynamic equilibrium at the interface.

AB - Atom probe tomography was utilized to measure directly the chemical compositions of Al3(Zr1-xTix) precipitates with a metastable Ll2 structure formed in Al-0. 1Zr-0.1Ti (at.%) alloys upon aging at 375°C or 425°C. The alloys exhibit an inhomogeneous distribution of Al3(Zr1-xTix) precipitates, as a result of a nonuniform dendritic distribution of solute atoms after casting. At these aging temperatures, the Zr:Ti atomic ratio in the precipitates is about 10 and 5, respectively, indicating that Ti remains mainly in solid solution rather than partitioning to the Al3(Zr1-xTix) precipitates. This is interpreted as being due to the very small diffusivity of Ti in α-Al, consistent with prior studies on Al-Sc-Ti and Al-Sc-Zr alloys, where the slower diffusing Zr and Ti atoms make up a small fraction of the Al3(Sc1-x/Tix/Zrx) precipitates. Unlike those alloys, however, the present Al-Zr-Ti alloys exhibit no interfacial segregation of Ti at the matrix/precipitate heterophase interface, a result that may be affected by a significant disparity in the evaporation fields of the α-Al matrix and Al3(Zr1-xTix) precipitates and/or a lack of local thermodynamic equilibrium at the interface.

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KW - AlZr precipitates

KW - Atom probe tomography

KW - Local magnification

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Atom probe tomographic studies of precipitation in Al-O. 1Zr-O. 1Ti (at.%) alloys

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Keywords

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