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Title: A high-resolution analytical scanning transmission electron microscopy study of the early stages of spinodal decomposition in binary Fe–Cr

Abstract

Spinodal decomposition (SD) is an important phenomenon in materials science and engineering. For example, it is considered to be responsible for the 475 °C embrittlement of stainless steels comprising the bcc (ferrite) or bct (martensite) phases. Structural characterization of the evolving minute nano-scale concentration fluctuations during SD in the Fe–Cr system is, however, a notable challenge, and has mainly been considered accessible via atom probe tomography (APT) and small-angle neutron scattering. The standard tool for nanostructure characterization, viz. transmission electron microscopy (TEM), has only been successfully applied to late stages of SD when embrittlement is already severe. However, we here demonstrate that the structural evolution in the early stages of SD in binary Fe–Cr, and alloys based on the binary, are accessible via analytical scanning TEM. An Fe–36 wt% Cr alloy aged at 500 °C for 1, 10 and 100 h is investigated using an aberration-corrected microscope and it is found that highly coherent and interconnected Cr-rich regions develop. The wavelength of decomposition is rather insensitive to the sample thickness and it is quantified to 2, 3 and 6 nm after ageing for 1, 10 and 100 h, which is in reasonable agreement with prior APT analysis. The concentration amplitudemore » is more sensitive to the sample thickness and acquisition parameters but the TEM analysis is in good agreement with APT analysis for the longest ageing time. These findings open up for combinatorial TEM studies where both local crystallography and chemistry is required. - Highlights: • STEM-EELS analysis was successfully applied to resolve early stage SD in Fe–Cr. • Compositional wavelength measured with STEM-EELS compares well to previous ATP studies. • Compositional amplitude measured with STEM-EELS is a function of experimental parameters. • STEM-EELS allows for combinatorial studies of SD using complementary techniques.« less

Authors:
 [1]; ;  [1]; ; ;  [2];  [3]
  1. Centre for High Resolution TEM, Nelson Mandela Metropolitan University, University Way, Port Elizabeth 6031 (South Africa)
  2. Dept. Materials Science and Engineering, KTH Royal Institute of Technology, Brinellvägen 23, 10044 Stockholm (Sweden)
  3. Nelson Mandela Metropolitan University, Gardham Av., Port Elizabeth 6031 (South Africa)
Publication Date:
OSTI Identifier:
22587053
Resource Type:
Journal Article
Resource Relation:
Journal Name: Materials Characterization; Journal Volume: 109; Other Information: Copyright (c) 2015 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 77 NANOSCIENCE AND NANOTECHNOLOGY; AMPLITUDES; BCC LATTICES; CRYSTALLOGRAPHY; DECOMPOSITION; EMBRITTLEMENT; FERRITES; MARTENSITE; NANOSTRUCTURES; NEUTRON DIFFRACTION; SMALL ANGLE SCATTERING; STAINLESS STEELS; TETRAGONAL LATTICES; TRANSMISSION ELECTRON MICROSCOPY

Citation Formats

Westraadt, J.E., E-mail: johan.westraadt@nmmu.ac.za, Olivier, E.J., Neethling, J.H., Hedström, P., Odqvist, J., Xu, X., and Steuwer, A. A high-resolution analytical scanning transmission electron microscopy study of the early stages of spinodal decomposition in binary Fe–Cr. United States: N. p., 2015. Web. doi:10.1016/J.MATCHAR.2015.10.001.
Westraadt, J.E., E-mail: johan.westraadt@nmmu.ac.za, Olivier, E.J., Neethling, J.H., Hedström, P., Odqvist, J., Xu, X., & Steuwer, A. A high-resolution analytical scanning transmission electron microscopy study of the early stages of spinodal decomposition in binary Fe–Cr. United States. doi:10.1016/J.MATCHAR.2015.10.001.
Westraadt, J.E., E-mail: johan.westraadt@nmmu.ac.za, Olivier, E.J., Neethling, J.H., Hedström, P., Odqvist, J., Xu, X., and Steuwer, A. Sun . "A high-resolution analytical scanning transmission electron microscopy study of the early stages of spinodal decomposition in binary Fe–Cr". United States. doi:10.1016/J.MATCHAR.2015.10.001.
@article{osti_22587053,
title = {A high-resolution analytical scanning transmission electron microscopy study of the early stages of spinodal decomposition in binary Fe–Cr},
author = {Westraadt, J.E., E-mail: johan.westraadt@nmmu.ac.za and Olivier, E.J. and Neethling, J.H. and Hedström, P. and Odqvist, J. and Xu, X. and Steuwer, A.},
abstractNote = {Spinodal decomposition (SD) is an important phenomenon in materials science and engineering. For example, it is considered to be responsible for the 475 °C embrittlement of stainless steels comprising the bcc (ferrite) or bct (martensite) phases. Structural characterization of the evolving minute nano-scale concentration fluctuations during SD in the Fe–Cr system is, however, a notable challenge, and has mainly been considered accessible via atom probe tomography (APT) and small-angle neutron scattering. The standard tool for nanostructure characterization, viz. transmission electron microscopy (TEM), has only been successfully applied to late stages of SD when embrittlement is already severe. However, we here demonstrate that the structural evolution in the early stages of SD in binary Fe–Cr, and alloys based on the binary, are accessible via analytical scanning TEM. An Fe–36 wt% Cr alloy aged at 500 °C for 1, 10 and 100 h is investigated using an aberration-corrected microscope and it is found that highly coherent and interconnected Cr-rich regions develop. The wavelength of decomposition is rather insensitive to the sample thickness and it is quantified to 2, 3 and 6 nm after ageing for 1, 10 and 100 h, which is in reasonable agreement with prior APT analysis. The concentration amplitude is more sensitive to the sample thickness and acquisition parameters but the TEM analysis is in good agreement with APT analysis for the longest ageing time. These findings open up for combinatorial TEM studies where both local crystallography and chemistry is required. - Highlights: • STEM-EELS analysis was successfully applied to resolve early stage SD in Fe–Cr. • Compositional wavelength measured with STEM-EELS compares well to previous ATP studies. • Compositional amplitude measured with STEM-EELS is a function of experimental parameters. • STEM-EELS allows for combinatorial studies of SD using complementary techniques.},
doi = {10.1016/J.MATCHAR.2015.10.001},
journal = {Materials Characterization},
number = ,
volume = 109,
place = {United States},
year = {Sun Nov 15 00:00:00 EST 2015},
month = {Sun Nov 15 00:00:00 EST 2015}
}