On the formation of hierarchically structured L21 -Ni 2TiAl type precipitates in a ferritic alloy

C. H. Liebscher; V. Radmilovic; U. Dahmen; M. Asta; G. Ghosh

doi:10.1007/s10853-012-6980-3

On the formation of hierarchically structured L2₁ -Ni ₂TiAl type precipitates in a ferritic alloy

C. H. Liebscher^*, V. Radmilovic, U. Dahmen, M. Asta, G. Ghosh

^*Corresponding author for this work

Materials Science and Engineering

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

39 Scopus citations

Abstract

This study demonstrates a processing sequence used to generate coherent, two-phase L2₁ -Ni₂TiAl/B2-NiAl precipitates in a ferritic matrix, and documents their microstructural evolution. Dark-field and energy-filtered transmission electron microscopy in combination with energy-dispersive X-ray analysis are used to determine the structure and composition of the different phases in the course of the processing and aging treatment. Through rapid solidification, coherent L2 ₁ -Ni ₂TiAl type precipitates with an internal network of curved, isotropic 1/2〈100〉 antiphase boundaries form within the bcc-Fe matrix. The average width of the precipitates in the as-quenched state is 15 nm. During the subsequent aging heat treatment thin, anisotropic B2-NiAl zones are established, resulting in a three-tiered hierarchical microstructure. The L2 ₁ -Ni₂TiAl precipitates are coherent with the bcc-Fe matrix, while the fine B2-NiAl zones are coherently embedded in the Ni₂TiAl precipitates and aligned along the 〈100〉 directions. The L2 ₁ -Ni₂TiAl parent precipitates have a width of 40 nm in the heat-treated stage and the B2-NiAl zones are 3-7 nm wide. Hence, the addition of Ti to Fe-rich Fe-Ni-Al alloys leads to the formation of coherent L2₁ -Ni₂TiAl precipitates in the bcc-Fe matrix with an internal network of fine, anisotropic B2-NiAl zones arranged in a hierarchical manner. These microstructures are of potential interest for designing and optimizing the mechanical properties of precipitation-strengthened ferritic alloys.

Original language	English (US)
Pages (from-to)	2067-2075
Number of pages	9
Journal	Journal of Materials Science
Volume	48
Issue number	5
DOIs	https://doi.org/10.1007/s10853-012-6980-3
State	Published - Mar 2013

Funding

Acknowledgements Originally, this work was supported by the Electric Power Research Institute under Grant#RP8043-1 (Dr. J. Stringer). The current research is supported by the National Energy Technology Laboratory (NETL) within the Office of Fossil Energy (FE) of the U.S. Department of Energy (DOE) under Grant No. DE-FE0005868. TEM investigations were performed at the National Center for Electron Microscopy (NCEM), which is supported by the Office of Science, Office of Basic Energy Sciences of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. We thank Mr. Mehner of Max-Planck Institute for Solid State Research (FKF), Stuttgart, for carrying out melt-spinning. We gratefully acknowledge helpful discussions with Prof. P. K. Liaw and Prof. David Dunand. VR acknowledges support by the Ministry of Education and Science of the Republic of Serbia, under project No. 172054 and Nanotechnology and Functional Materials Center, funded by the EC FP7 project No. 245916.

ASJC Scopus subject areas

Mechanics of Materials
Ceramics and Composites
Mechanical Engineering
Polymers and Plastics
General Materials Science
Materials Science (miscellaneous)

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10.1007/s10853-012-6980-3

Cite this

@article{21842c646e6548dbb5beb2c2f5fa3267,

title = "On the formation of hierarchically structured L21 -Ni 2TiAl type precipitates in a ferritic alloy",

abstract = "This study demonstrates a processing sequence used to generate coherent, two-phase L21 -Ni2TiAl/B2-NiAl precipitates in a ferritic matrix, and documents their microstructural evolution. Dark-field and energy-filtered transmission electron microscopy in combination with energy-dispersive X-ray analysis are used to determine the structure and composition of the different phases in the course of the processing and aging treatment. Through rapid solidification, coherent L2 1 -Ni 2TiAl type precipitates with an internal network of curved, isotropic 1/2〈100〉 antiphase boundaries form within the bcc-Fe matrix. The average width of the precipitates in the as-quenched state is 15 nm. During the subsequent aging heat treatment thin, anisotropic B2-NiAl zones are established, resulting in a three-tiered hierarchical microstructure. The L2 1 -Ni2TiAl precipitates are coherent with the bcc-Fe matrix, while the fine B2-NiAl zones are coherently embedded in the Ni2TiAl precipitates and aligned along the 〈100〉 directions. The L2 1 -Ni2TiAl parent precipitates have a width of 40 nm in the heat-treated stage and the B2-NiAl zones are 3-7 nm wide. Hence, the addition of Ti to Fe-rich Fe-Ni-Al alloys leads to the formation of coherent L21 -Ni2TiAl precipitates in the bcc-Fe matrix with an internal network of fine, anisotropic B2-NiAl zones arranged in a hierarchical manner. These microstructures are of potential interest for designing and optimizing the mechanical properties of precipitation-strengthened ferritic alloys.",

author = "Liebscher, {C. H.} and V. Radmilovic and U. Dahmen and M. Asta and G. Ghosh",

note = "Funding Information: Acknowledgements Originally, this work was supported by the Electric Power Research Institute under Grant#RP8043-1 (Dr. J. Stringer). The current research is supported by the National Energy Technology Laboratory (NETL) within the Office of Fossil Energy (FE) of the U.S. Department of Energy (DOE) under Grant No. DE-FE0005868. TEM investigations were performed at the National Center for Electron Microscopy (NCEM), which is supported by the Office of Science, Office of Basic Energy Sciences of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. We thank Mr. Mehner of Max-Planck Institute for Solid State Research (FKF), Stuttgart, for carrying out melt-spinning. We gratefully acknowledge helpful discussions with Prof. P. K. Liaw and Prof. David Dunand. VR acknowledges support by the Ministry of Education and Science of the Republic of Serbia, under project No. 172054 and Nanotechnology and Functional Materials Center, funded by the EC FP7 project No. 245916.",

year = "2013",

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doi = "10.1007/s10853-012-6980-3",

language = "English (US)",

volume = "48",

pages = "2067--2075",

journal = "Journal of Materials Science",

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T1 - On the formation of hierarchically structured L21 -Ni 2TiAl type precipitates in a ferritic alloy

AU - Liebscher, C. H.

AU - Radmilovic, V.

AU - Dahmen, U.

AU - Asta, M.

AU - Ghosh, G.

N1 - Funding Information: Acknowledgements Originally, this work was supported by the Electric Power Research Institute under Grant#RP8043-1 (Dr. J. Stringer). The current research is supported by the National Energy Technology Laboratory (NETL) within the Office of Fossil Energy (FE) of the U.S. Department of Energy (DOE) under Grant No. DE-FE0005868. TEM investigations were performed at the National Center for Electron Microscopy (NCEM), which is supported by the Office of Science, Office of Basic Energy Sciences of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. We thank Mr. Mehner of Max-Planck Institute for Solid State Research (FKF), Stuttgart, for carrying out melt-spinning. We gratefully acknowledge helpful discussions with Prof. P. K. Liaw and Prof. David Dunand. VR acknowledges support by the Ministry of Education and Science of the Republic of Serbia, under project No. 172054 and Nanotechnology and Functional Materials Center, funded by the EC FP7 project No. 245916.

PY - 2013/3

Y1 - 2013/3

N2 - This study demonstrates a processing sequence used to generate coherent, two-phase L21 -Ni2TiAl/B2-NiAl precipitates in a ferritic matrix, and documents their microstructural evolution. Dark-field and energy-filtered transmission electron microscopy in combination with energy-dispersive X-ray analysis are used to determine the structure and composition of the different phases in the course of the processing and aging treatment. Through rapid solidification, coherent L2 1 -Ni 2TiAl type precipitates with an internal network of curved, isotropic 1/2〈100〉 antiphase boundaries form within the bcc-Fe matrix. The average width of the precipitates in the as-quenched state is 15 nm. During the subsequent aging heat treatment thin, anisotropic B2-NiAl zones are established, resulting in a three-tiered hierarchical microstructure. The L2 1 -Ni2TiAl precipitates are coherent with the bcc-Fe matrix, while the fine B2-NiAl zones are coherently embedded in the Ni2TiAl precipitates and aligned along the 〈100〉 directions. The L2 1 -Ni2TiAl parent precipitates have a width of 40 nm in the heat-treated stage and the B2-NiAl zones are 3-7 nm wide. Hence, the addition of Ti to Fe-rich Fe-Ni-Al alloys leads to the formation of coherent L21 -Ni2TiAl precipitates in the bcc-Fe matrix with an internal network of fine, anisotropic B2-NiAl zones arranged in a hierarchical manner. These microstructures are of potential interest for designing and optimizing the mechanical properties of precipitation-strengthened ferritic alloys.

AB - This study demonstrates a processing sequence used to generate coherent, two-phase L21 -Ni2TiAl/B2-NiAl precipitates in a ferritic matrix, and documents their microstructural evolution. Dark-field and energy-filtered transmission electron microscopy in combination with energy-dispersive X-ray analysis are used to determine the structure and composition of the different phases in the course of the processing and aging treatment. Through rapid solidification, coherent L2 1 -Ni 2TiAl type precipitates with an internal network of curved, isotropic 1/2〈100〉 antiphase boundaries form within the bcc-Fe matrix. The average width of the precipitates in the as-quenched state is 15 nm. During the subsequent aging heat treatment thin, anisotropic B2-NiAl zones are established, resulting in a three-tiered hierarchical microstructure. The L2 1 -Ni2TiAl precipitates are coherent with the bcc-Fe matrix, while the fine B2-NiAl zones are coherently embedded in the Ni2TiAl precipitates and aligned along the 〈100〉 directions. The L2 1 -Ni2TiAl parent precipitates have a width of 40 nm in the heat-treated stage and the B2-NiAl zones are 3-7 nm wide. Hence, the addition of Ti to Fe-rich Fe-Ni-Al alloys leads to the formation of coherent L21 -Ni2TiAl precipitates in the bcc-Fe matrix with an internal network of fine, anisotropic B2-NiAl zones arranged in a hierarchical manner. These microstructures are of potential interest for designing and optimizing the mechanical properties of precipitation-strengthened ferritic alloys.

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