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Author |
Cautaerts, N.; Delville, R.; Stergar, E.; Schryvers, D.; Verwerft, M. |
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Title |
Characterization of (Ti,Mo,Cr)C nanoprecipitates in an austenitic stainless steel on the atomic scale |
Type |
A1 Journal article |
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Year  |
2019 |
Publication |
Acta materialia |
Abbreviated Journal |
Acta Mater |
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Volume |
164 |
Issue |
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Pages |
90-98 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) |
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Abstract |
Nanometer sized (Ti,Mo,Cr)C (MX-type) precipitates that grew in a 24% cold worked Ti-stabilized austenitic stainless steel (grade DIN 1.4970, member of the 15-15Ti austenitic stainless steels) after heat treatment were fully characterized with transmission electron microscopy (TEM), probe corrected high angle annular dark field scanning transmission electron microscopy (HR-HAADF STEM), and atom probe tomography (APT). The precipitates shared the cube-on-cube orientation with the matrix and were facetted on {111} planes, yielding octahedral and elongated octahedral shapes. The misfit dislocations were believed to have Burgers vectors a/6<112> which was verified by geometrical phase analysis (GPA) strain mapping of a matrix-precipitate interface. The dislocations were spaced five to seven atomic
planes apart, on average slightly wider than expected for the lattice parameters of steel and TiC. Quantitative atom probe tomography analysis of the precipitates showed that precipitates were significantly enriched in Mo, Cr and V, and that they were hypostoichiometric with respect to C. These findings were consistent with a reduced lattice parameter. The precipitates were found primarily on Shockley
partial dislocations originating from the original perfect dislocation network. These novel findings could contribute to the understanding of how TiC nanoprecipitates interact with point defects and matrix dislocations. This is essential for the application of these Ti-stabilized steels in high temperature environments or fast spectrum nuclear fission reactors. |
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Wos |
000456902800008 |
Publication Date |
2018-10-11 |
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Edition |
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ISSN |
1359-6454 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
5.301 |
Times cited |
2 |
Open Access |
Not_Open_Access: Available from 12.10.2020
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Notes |
This work was supported by ENGIE [contract number 2015-AC- 007 e BSUEZ6900]; the U.S. Department of Energy, Office of Nuclear Energy under DOE Idaho Operations Office Contract DE-AC07- 051D14517 as part of a Nuclear Science User Facilities experiment; and by the MYRRHA program in development at SCKCEN, Belgium. Special thanks to Dr. H. Mezerji and Dr. T. Altantzis for the work on the FEI Titan microscope.We also want to thank Ms. J. Burns for the help on the FIB and Dr. Y. Wu at CAES for conducting the APT measurements. |
Approved |
Most recent IF: 5.301 |
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Call Number |
EMAT @ emat @c:irua:154873UA @ admin @ c:irua:154873 |
Serial |
5060 |
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Author |
Cautaerts, N.; Delville, R.; Stergar, E.; Schryvers, D.; Verwerft, M. |
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Title |
Tailoring the Ti-C nanoprecipitate population and microstructure of titanium stabilized austenitic steels |
Type |
A1 Journal article |
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Year |
2018 |
Publication |
Journal of nuclear materials |
Abbreviated Journal |
J Nucl Mater |
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Volume |
507 |
Issue |
507 |
Pages |
177-187 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) |
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Abstract |
The present work reports on the microstructural evolution of a new heat of 24% cold worked austenitic DIN 1.4970 (15-15Ti) nuclear cladding steel subjected to ageing heat treatments of varying duration between 500 and 800 degrees C (by steps of 100 degrees C). The primary aim was studying the finely dispersed Ti-C nanoprecipitate population, which are thought to be beneficial for creep and swelling resistance during service. Their size distribution and number density were estimated through dark field imaging and bright field Moire imaging techniques in the transmission electron microscope. Nanoprecipitates formed at and above 600 degrees C, which is a lower temperature than previously reported. The observed nucleation, growth and coarsening behavior of the nanoprecipitates were consistent with simple diffusion arguments. The formation of nanoprecipitates coincided with significant dissociation of dislocations as evidenced by weak beam dark field imaging. Possible mechanisms, including Silcock's stacking fault growth model and Suzuki segregation, are discussed. Recrystallization observed after extended ageing at 800 degrees C caused the redissolution of nanoprecipitates. Large primary Ti(C,N) and (Ti,Mo)C precipitates that occur in the as-received material, and M23C6 precipitates that nucleate on grain boundaries at low temperatures were also characterized by a selective dissolution procedure involving filtration, X-ray diffraction and quantitative Rietveld refinement. The partitioning of key elements between the different phases was derived by combining these findings and was consistent with thermodynamic considerations and the processing history of the steel. (C) 2018 Elsevier B.V. All rights reserved. |
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Place of Publication |
Amsterdam |
Editor |
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Wos |
000438019800021 |
Publication Date |
2018-04-30 |
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ISSN |
0022-3115 |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
2.048 |
Times cited |
1 |
Open Access |
Not_Open_Access |
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Notes |
; We would like to acknowledge ENGIE, SCK.CEN, the SCK.CEN academy and the MYRRHA project for the financial support of this work. Special thanks to T. Wangle and P. Dries for their help with filtration and gravimetry. Also thanks to Dr. G. Leinders for the discussions on XRD and Rietveld refinement. Thanks to E. Charalampopoulou and A. Youssef for assisting with the dissolution experiments. ; |
Approved |
Most recent IF: 2.048 |
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Call Number |
UA @ lucian @ c:irua:152382 |
Serial |
5043 |
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