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

Westraadt, Johan Ewald; Olivier, E.J.; Neethling, J.H.; Hedström, Peter; Odqvist, Joakim; Xu, Xin; Steuwer, A.

doi:10.1016/j.matchar.2015.10.001

Cited by 37 publications

(29 citation statements)

References 19 publications

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“…[13,14] It should be noted that the length-scale cannot be determined by MS. On the other hand, the high sensitivity of MS means that it can be used to investigate atomic short-range order, such as clustering above the miscibility gap. [36] The application of TEM, [4,5,[15][16][17] neutron diffraction (ND), [37,38] and SANS [23][24][25] to phase separation in Fe-Cr alloys is also well established. SANS can provide the length-scale of phase decomposition, whereas TEM and ND are used mainly as qualitative tools to detect whether phase separation has occurred.…”

Section: Experimental Methods For Characterization Of Phase Separmentioning

confidence: 99%

“…These technical developments have also been utilized to investigate phase separation in Fe-Cr alloys. [17,25] Although there has been significant progress, each technique still has limitations. For instance, TEM is often considered to be the standard tool for investigating nano-scale microstructural features, but the analysis of the Fe-Cr system is particularly difficult.…”

Section: Experimental Methods For Characterization Of Phase Separmentioning

confidence: 99%

“…There is a very small difference in atomic size between Fe and Cr and their atomic scattering factors are similar; thus, the coherency is high and the phase contrast is very low. [17] It has been found that the decomposition can still be characterized by orienting the sample along its softest direction of the bcc crystal h100i where the minor coherency strains are best visualized. [16] This approach is most effective in multicomponent alloys where the difference between a and a¢ phases may be slightly larger due to partitioning of the alloying elements.…”

Section: Experimental Methods For Characterization Of Phase Separmentioning

confidence: 99%

“…In the following text, we present new SANS measurements and analysis, conducted using a pulsed neutron source and the time-offlight technique, which allows the detection of phase separation over a wide range of length scales simultaneously, and compare these results with our prior measurements using TEM and APT. [17,29,32] …”

Section: Experimental Methods For Characterization Of Phase Separmentioning

confidence: 99%

“…[3] Due to the high technical relevance and its suitability as a model material for phase separation studies, binary Fe-Cr alloys have been extensively investigated. Theoretical tools such as phase-field modeling [4][5][6] and kinetic Monte Carlo [7][8][9][10] are frequently adopted to simulate the nanostructure evolution, and experimental tools such as Mo¨ssbauer spectroscopy (MS), [11][12][13][14] transmission electron microscopy (TEM), [4,5,[15][16][17] small-angle neutron scattering (SANS), [18][19][20][21][22][23][24][25] atom probe field ion microscopy (APFIM), [7][8][9]26,27] and later atom probe tomography (APT) [10,[28][29][30][31][32][33][34] have been applied. Most of the studies in the literature focus on the rather late stages of phase decomposition, when the embrittlement is already severe, and today it is still considered a major challenge to quantitatively characterize the nanostructure in technically relevant cases, when the length-scale is in the order of a few atomic distances and the concentration variations between a and a¢ are only a few atomic percent.…”

Section: Introductionmentioning

confidence: 99%

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Structural Characterization of Phase Separation in Fe-Cr: A Current Comparison of Experimental Methods

Odqvist

Colliander

et al. 2016

Metall Mater Trans A

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Self-assembly due to phase separation within a miscibility gap is important in numerous material systems and applications. A system of particular interest is the binary alloy system Fe-Cr, since it is both a suitable model material and the base system for the stainless steel alloy category, suffering from low-temperature embrittlement due to phase separation. Structural characterization of the minute nano-scale concentration fluctuations during early phase separation has for a long time been considered a major challenge within material characterization. However, recent developments present new opportunities in this field. Here, we present an overview of the current capabilities and limitations of different techniques. A set of Fe-Cr alloys were investigated using small-angle neutron scattering (SANS), atom probe tomography, and analytical transmission electron microscopy. The complementarity of the characterization techniques is clear, and combinatorial studies can provide complete quantitative structure information during phase separation in Fe-Cr alloys. Furthermore, we argue that SANS provides a unique in-situ access to the nanostructure, and that direct comparisons between SANS and phase-field modeling, solving the non-linear Cahn Hilliard equation with proper physical input, should be pursued.

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Section: Experimental Methods For Characterization Of Phase Separmentioning

confidence: 99%

Section: Experimental Methods For Characterization Of Phase Separmentioning

confidence: 99%

Section: Experimental Methods For Characterization Of Phase Separmentioning

confidence: 99%

Section: Experimental Methods For Characterization Of Phase Separmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Structural Characterization of Phase Separation in Fe-Cr: A Current Comparison of Experimental Methods

Odqvist

Colliander

et al. 2016

Metall Mater Trans A

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Thermally Decomposed Binary Fe–Cr Alloys: Toward a Quantitative Relationship Between Strength and Structure

et al. 2021

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Binary Fe-Cr alloys represent model alloys for ferritic/martensitic steels, which have been considered for structural applications in future thermonuclear fusion reactors since the late 1970s, [1] due to their excellent thermal properties, corrosion properties, and swelling resistance under irradiation compared with austenitic steels. [1][2][3] One of the main challenges in this context is that structural materials in such reactors are expected to be exposed to temperatures where Cr segregation or even decomposition in Ferich α regions and Cr-rich α 0 regions can occur, inducing the known "475 C embrittlement." [4,5] This causes a hardening of over 100% and a drop in impact strength by orders of magnitude. [5,6] Extensive irradiation, with a lattice damage of over 100 displacements per atom (dpa) caused by fusion neutrons, [3] adds another factor that potentially contributes to αÀα 0 decomposition. The Cr content of the relevant steels is typically set at around 10 wt% to achieve suitable corrosion resistance and above, as in oxide dispersion strengthened steels, [7] to avoid the γ-loop in case of an accidental excursion to high temperature. However, this also places them in a situation where the αÀα 0 decomposition becomes an issue, [8] as observed in a neutron-irradiated 9 wt% Cr model alloy. [9] It is therefore essential to mitigate the decomposition, starting with the investigation of Fe-Cr model alloys to avoid the complexity of steels that hinders the identification of the underlying fundamental mechanisms. This can in turn help understand Cr segregation and its interplay with irradiation-induced lattice defects, [10] which can have similar deleterious effects on mechanical properties. That is critical to optimize ferritic/martensitic steels for fusion reactors.475 C embrittlement was identified in the 1950s [4] as a phenomenon that is unrelated to the formation of the intermetallic σ phase, and the idea of the miscibility gap was firmly established soon after. [5] At that point, the essential concepts surrounding this phenomenon were settled, which relate to the αÀα 0 separation, governed by chemical and magnetic energies. [5,11] Research continued in the following decades, often focusing on mechanical properties. [6,[12][13][14] Mössbauer spectroscopy and neutron scattering were common tools for obtaining information on the nanoscale structure. However, methods for detailed direct imaging were not available until the early 1990s, when advancements in atom probe tomography (APT) enabled 3D atomic mapping of the decomposed structures. [15,16] APT has since then become the most prominent method in the field.In recent times, APT has been used extensively to resolve the decomposed αÀα 0 structure, in, for example, the works of Novy et al., [17] Tissot et al., [18] and Reese et al. [19] . The first two studies showed detailed APT analyses of 20 and 19 at% Fe-Cr alloys annealed at 500 C for up to about 1000 h. They agree well with each other and with previous work [13] concerning the equilibrium compositions at ...

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Thermally Decomposed Binary Fe–Cr Alloys: Toward a Quantitative Relationship Between Strength and Structure

et al. 2022

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

Cited by 37 publications

References 19 publications

Structural Characterization of Phase Separation in Fe-Cr: A Current Comparison of Experimental Methods

Structural Characterization of Phase Separation in Fe-Cr: A Current Comparison of Experimental Methods

Thermally Decomposed Binary Fe–Cr Alloys: Toward a Quantitative Relationship Between Strength and Structure

Thermally Decomposed Binary Fe–Cr Alloys: Toward a Quantitative Relationship Between Strength and Structure

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