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All issues Volume 12 (2026) EPJ Nuclear Sci. Technol., 12 (2026) 21 Full HTML
Open Access
Issue
EPJ Nuclear Sci. Technol.
Volume 12, 2026
Article Number 21
Number of page(s) 10
DOI https://doi.org/10.1051/epjn/2026013
Published online 26 June 2026

© I.W. Ngarayana et al., Published by EDP Sciences, 2026

Licence Creative CommonsThis is an Open Access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

1. Introduction

Material advancement for nuclear reactor’s application is a key element for improving safety features of nuclear power plants (NPPs) [1]. Any failure related to fuel assembly’s materials during normal operation or accident may lead to an unacceptable radiological consequence [2]. The catastrophic Fukushima Daiichi nuclear accident in 2011 catalyzed substantial advancements in the development of accident-tolerant fuels (ATFs) for light-water reactors (LWRs) [3–8]. A critical safety concern that emerged during the accident was the interaction between Zircaloy cladding and steam, which resulted in an exothermic reaction and hydrogen gas generation [9–11]. The accumulation of hydrogen resulted in explosions, significantly intensifying the accident’s severity [12]. Consequently, substantial efforts have been invested for enhancing the resilience of nuclear fuel cladding materials [13].

Thumbnail: Fig. 1. Refer to the following caption and surrounding text. Fig. 1.

A typical assembly of a pressurized water reactor used in the Monte Carlo simulations. Unit is centimeters.

One strategy involves applying protective layers to Zircaloy to mitigate its reactivity with steam [14]. The protective layers are considered as a quick solution implementable without any major changes required to compensate the current fuel’s design which also affect the related licensing procedures. However, to achieve better performance and safety, the development of novel cladding materials, such as FeCrAl alloys, is preferably considered [15–17]. FeCrAl alloys exhibit exceptional high-temperature oxidation resistance and mechanical properties, which are necessary for ATFs candidates [18].

Several studies have been performed to get appropriate FeCrAl for fuel cladding. One study found that the addition of silicon (Si) as a solute in ferritic alloys could enhance their corrosion resistance [19]. The addition of Si was also found that it can improve the confinement of fission products, such as cesium [20, 21]. This is crucial for preventing the release of harmful fission products to the environment especially during an accident [22–24]. It was also found that Si solutes may also change the mechanical, and physical properties of FeCrAl alloys, contributing to their overall performance and safety in nuclear reactors [13, 19, 25–27]. However, these issues are still not well investigated and further research is necessary to fully explore these potential effects.

This study explored the properties of FeCrAl alloys with varying Si content up to 8.00 wt.% through computational and experimental studies. The initial compositions of FeCrAl were selected based on ternary phase diagrams produced by FactSage [28, 29], and insights from previous research [30, 31]. Monte Carlo simulations using OpenMC were employed to investigate the neutronic performance of these compositions. The experimental studies were involved for synthesizing and characterizing these alloys [32].

This study was focused on providing a thorough understanding of the impacts of Si solute variations on the neutronic and microstructure behaviors of FeCrAl alloys. The ultimate objective was to develop the more accident tolerant nuclear fuel claddings.

2. Methodology

2.1. Monte Carlo simulations

To investigate the neutronic properties of these FeCrAl alloys, Monte Carlo simulations using OpenMC code was employed [32]. The simulations were set up to evaluate key parameters, e.g. the neutron multiplication factor (k) and the depletion time. The input parameters and geometric configurations were based on a fuel assembly of a typical pressurized water reactor (PWR) AP-1000 model in Figure 1 [33]. The assembly has a 17 × 17 pins configuration, with 264 fuel pins and the rest were filled completely by water with a density of 0.7295 g/cm3. The designated fuel was uranium oxide (UO2) enriched to 4.95 wt.% of 235U with a density of 11.05 g/cm3, which is corresponding to near-theoretical UO2 density (theoretical value in cubic crystal structure is about 11.26 g/cm3). Helium (He) gas with a density of 0.00016 g/cm3 was placed in between the UO2 and the cladding (ref. Fig. 1). The UO2, He and the cladding were modeled at 900 K while the water was modeled at 600 K.

This work did not use a full core model of the PWR for the Monte Carlo fuel depletion simulations. Instead, it used only a single assembly for an infinite lattice reactor calculation technique. Hence, the simulations calculated an infinite neutron multiplication factor (kinf). This was done by deploying reflective boundary conditions for the radial sides of the fuel assembly, while the top and bottom sides were assigned to a vacuum boundary condition. Since there is only one fuel assembly, the power rating assigned to the model was 21.65 MWt referring to AP-1000 reactor’s specification rated at 3400 MWt with 157 fuel assemblies.

Five fuel depletion simulations were completed to observe the effect of Si in the FeCrAl cladding subsystem and the effect of FeCrAl itself compared to the typical Zr-4 cladding (density of 6.55 g/cm3). One simulation was using the Zr-4 cladding, and four other simulations were using FeCrAl with 0 wt.%, 0.50 wt.%, 2.00 wt.%, and 8.00 wt.% of the added Si with their theoretical densities (ref. Fig. 4). All simulations used the same geometry of the fuel assembly model. Each simulation was bound to have a standard deviation for kinf of less than 50 per cent mille. The simulations used ENDF/B-VII.1 nuclear data [34]. This work used a recommended depletion chain from the Consortium for the Advanced Simulations of Light water reactors (CASL) for a generic depletion simulation [35]. The depletion calculations were in several time steps using a first-order predictor algorithm [35]. Generally, the algorithm solves the depletion problem in two steps: the prediction step calculates a rough approximation of the desired quantities, and the corrector step refines the initial approximation.

Table 1.

Composition of synthesized FeCrAl specimens. Cr and Al are maintained at 12.50 wt.%, and 4.50 wt.%, respectively. Si content varies between 0 and 8.00 wt.%, while Fe constitutes the remaining composition.

2.2. Experiment procedure

2.2.1. Received materials

The material used for the experimental works competed in this study were supplied by different manufacturers. Fe and Al with a purity of 99.0% and particle sizes of approximately 60- and 44-μm, respectively, were provided by GoodFellow Cambridge Limited. Cr with a purity of 99.0% and a particle size of 44 μm, was supplied by Alfa Aesar. The Si with a purity of 99.5% and a particle size of 44 μm was supplied by Sigma Aldrich.

2.2.2. Synthesis

All precursors were carefully weighed and mixed in a mortal ceramic for 1 h to ensure homogeneity, with detailed compositions in Table 1. The mixed powders were then mechanically pressed at 100 kN to form green pellets with a diameter of 10 mm. Subsequently, the green pellets were sintered in a furnace filled with argon gas at a flow rate of approximately 10 ml/min. The designated furnace temperature setting is in Figure 2. The furnace temperature was gradually increased from room temperature to 660 °C in one hour and was maintained at this temperature for three hours. Subsequently, the temperature was raised from 660 °C to 900 °C in one hour and was held at this temperature for six hours. Finally, the temperature was raised from 900 °C to 1100 °C in one additional hour and was maintained at this temperature for three hours. The furnace temperature was then gradually reduced to room temperature. Finally, the sintered pellets were melted using an arc melting technique under an argon atmosphere at a current of 100 A and a voltage of 15 V for one minute. This process was repeated up to five times to ensure the synthesized material’s homogeneity.

2.2.3. Polishing and etching

Prior to characterization, all final specimens underwent a series of grinding and polishing processes. The initial grinding was conducted using silicon carbide paper with particle sizes ranging from 40- to 5-μm. The specimens were further polished with diamond abrasives of 1 μm. Then, the specimens were thoroughly rinsed using water, ethanol, and acetone to eliminate any remaining impurities.

The well-polished specimens were subsequently immersed in an etching solution for approximately one minute and were then rinsed using alcohol. The etching was performed using a mixture of hydrochloric acid (HCl) and nitric acid (HNO3) solutions with a ratio of 1:3 and a concentration of about 37% and 66%, respectively.

Thumbnail: Fig. 2. Refer to the following caption and surrounding text. Fig. 2.

The furnace was operated with an argon flow rate of approximately 10 ml/min. The temperature was gradually increased from room temperature to 660 °C for one hour, then maintained at that temperature for three hours. Subsequently, the temperature was raised to 900 °C for another hour and held for six hours. This process was repeated, with the temperature increasing to 1100 °C for one hour and held for three hours. Finally, the furnace was allowed to cool down to room temperature at a controlled rate.
Thumbnail: Fig. 3. Refer to the following caption and surrounding text. Fig. 3.

Infinite neutron multiplication factor of the assembly models with various cladding sub-system. In comparison to the Zr-4 system, the FeCrAl cladding system generally exhibits a significantly lower kinf. Notably, the incorporation of Si as solute element into FeCrAl leads to a modest increase in the kinf. This is due to the reduction in Fe content.

2.2.4. Characterization

The specimens were characterized utilizing Optical Microscopy (OM), Scanning Electron Microscope/Energy Dispersive X-Ray Spectroscopy (SEM/EDS), X-Ray Diffraction (XRD), and the Micro Vickers Hardness test to identify the grain size, elemental distribution, crystallographic, as well as their mechanical properties.

Olympus U-MSSPG OM was primarily utilized for polishing and etching. The OM possesses the capability to operate at magnifications ranging from 50- to 1000-times. Grain size measurements were obtained from images captured by OM and analyzed using ImageJ [36], adhering to the guidelines provided in ASTM E112-24 [37] by taking 70 lines of measurement for each specimen.

Jeol JSM-6510LA SEM machine was operated at an accelerating voltage of 20 kV and an irradiating current of 7.475 nA to observe the detailed surface morphology of the specimens. Elemental distribution identification was conducted using EDS.

Thumbnail: Fig. 4. Refer to the following caption and surrounding text. Fig. 4.

The density of specimens varies depending on the Si content. Specimens with higher Si content exhibit lower density, which can be attributed to the low density of Si. Theoretical density calculated based on the fraction of pure elements is typically within the measurement uncertainty range.
Thumbnail: Fig. 5. Refer to the following caption and surrounding text. Fig. 5.

Optical microscope images of synthesized FeCrAl specimens: (a) without Si, (b) with 0.25 wt.% Si, (c) 0.50 wt.% Si, (d) 1.00 wt.% Si, (e) 2.00 wt.% Si, (f) 4.00 wt.% Si, and (g) 8.00 wt.% Si. As the Si content increases, the grain size in the specimens decreases.
Thumbnail: Fig. 6. Refer to the following caption and surrounding text. Fig. 6.

Grain size distribution of FeCrAl specimens: (a) without Si, (b) with 0.25 wt.% Si, (c) 0.50 wt.% Si, (d) 1.00 wt.% Si, (e) 2.00 wt.% Si, (f) 4.00 wt.% Si, and (g) 8.00 wt.% Si. Specimens with higher Si content exhibit smaller grain sizes.
Thumbnail: Fig. 7. Refer to the following caption and surrounding text. Fig. 7.

SEM/EDS observation of synthesized FeCrAl specimens after etching at 2000 times magnification: (a) without Si, (b) with 0.25 wt.% Si, (c) 0.50 wt.% Si, (d) 1.00 wt.% Si, (e) 2.00 wt.% Si, (f) 4.00 wt.% Si, and (g) 8.00 wt.% Si. Well-defined grains are discernible from all specimens. EDS analysis reveals the relatively uniform distribution of all elements. Notably, in the specimen devoid of Si, surface is very coarse. As the concentration of Si increases, the coarseness of the surface decrease accordingly.
Thumbnail: Fig. 8. Refer to the following caption and surrounding text. Fig. 8.

XRD analysis of FeCrAl specimens with varying Si content (a) from 2θ = 30° to 90° and (b) zoomed in at 2θ = 43.6° to 45.4° reveals a consistent BCC structure. However, peaks shifting rightward suggest lattice structure changes due to the addition of Si solute.
Thumbnail: Fig. 9. Refer to the following caption and surrounding text. Fig. 9.

Impact of Si content on the Vickers hardness of FeCrAl specimens. As the Si content increases, the Vickers hardness values also increase linearly.

Malvern Panalytical XRD machine was operated to determine the crystalline structure of the specimens. The machine was operated with Cu-Kα radiation (λ = 0.154059 nm) at an accelerating voltage of 60 kV and a current of 100 mA. Data acquisition was conducted at 2θ values in the range of 20°–90° with a step size of 1.250° and a collection time of 2.5 s per step.

A Vickers Hardness Tester (Model HV-1000) was employed to conduct the hardness test. The machine was operated with a load of 1.96122 N and a dwell time of 10 s at room temperature.

Additional density measurements were conducted using Archimedes’ principle for all specimens immediately after melting. Mass measurements were performed using a 10−4 g precise analytical balance, while volume measurements were made by submerging the specimen in a volumetric glass filled with water, ensuring a precision of approximately 0.5 mL. For Monte Carlo simulations purposes, the theoretical densities were used and were calculated based on the fraction of pure elements, with the following formula [38]:

ρ = 1 ∑ ( W i ρ i ) Mathematical equation: $$ \begin{aligned} \rho =\frac{1}{\sum {\left(\frac{W_i}{{\rho }_i}\right)}} \end{aligned} $$

where:

ρ = theoretical density.

Wi = weight fraction of element i in the alloy.

ρi = density of pure element i.

3. Results

3.1. Neutronic properties prediction

The Monte Carlo simulations results show that the FeCrAl cladding system has far smaller kinf values compared to the one of the Zr-4 system. This automatically decreased the maximum period of fuel discharge to about 830 days, compared to the 1160 days of the Zr-4 system (ref. Fig. 3). With the addition of Si to the FeCrAl system, the kinf was slightly increased. This addition was compensated by the subtraction of the Fe amount in the system to maintain the Cr and Al quantities. Although Fe isotopes are well-considered neutron moderators, they have significantly higher neutron captures compared to Zr isotopes, especially at thermal energies.

3.2. Microstructural evolution

Figure 4 illustrates the density of FeCrAl specimens varying with different Si contents. When Si content increases, the density of the specimens decreases. Specimens with higher Si content exhibit lower densities due to the inherent low density of Si. The pure elemental density of Si is 2.33 g/cm3, whereas the density of Fe, Cr, and Al are approximately 7.87-, 7.14-, and 2.70-g/cm3, respectively [39]. Most mean values of the measured densities were generally found higher than theoretical one calculated based on the fraction of pure elements one. However, the theoretical values fall within the uncertainty’s range of the measured densities, with a confident interval of 99%. Aside from the significant range of the uncertainties, it is important to note that this theoretical density calculation does not account the possible interstitial phenomena of Si and/or Al atoms within the cubic structure of Fe and Cr.

Some optical micrographs of FeCrAl specimens were obtained with a magnification of 50 times (ref. Fig. 5). Differences in grain sizes are observable in samples with different Si contents. The sample without Si exhibits relatively larger grain sizes among all, indicating minimal refinement. As the Si content increases, there are noticeable reductions in grain size with finer and distinctive grain boundaries. This trend is persistent with higher Si concentrations, where the 8.00 wt.% Si sample has the finest grain structures. These refinements suggest different mechanical properties of the synthesized alloys.

Figure 6 presents the grain size distribution of FeCrAl specimens acquired through OM. The average grain size of the specimen without Si is 498 ± 135 μm, while for specimens with 0.25 wt.%, 0.50 wt.%, 1.00 wt.%, 2.00 wt.%, 4.00 wt.%, and 8.00 wt.% Si content, the average grain sizes are 335 ± 116 μm, 280 ± 89 μm, 258 ± 69 μm, 232 ± 70 μm, 227 ± 91 μm, and 201 ± 67 μm, respectively, within a confident level of 68%. This measurement clearly demonstrates that specimens with higher silicon content exhibit smaller and more refined grains.

Figure 7 presents SEM/EDS observations of FeCrAl specimens magnified to 2000 times. The figure encompasses images of the specimens with varying Si content: (a) without Si, (b) containing 0.25 wt.%, (c) 0.50 wt.%, (d) 1.00 wt.%, (e) 2.00 wt.%, (f) 4.00 wt.%, and (g) 8.00 wt.% Si. Across all specimens, well-defined grains are discernible. The specimen without Si exhibits the coarsest surface. As the Si content increased, the surface of specimens became progressively finer. This phenomenon is likely attributable to the enhancement of corrosion resistance during the etching process due to the presence of Si. The EDS maps elucidate the spatial distribution of Al, Si, Cr, and Fe. Notably, the elemental maps demonstrate a relatively uniform distribution of all elements throughout the microstructure. However, particularly in specimen with a Si content of 8.00 wt.%, Si is not evenly distributed. Several regions exhibiting high Si concentrations can be observed obviously in a distinctive area (ref. Fig. 7).

Figure 8 presents the XRD analysis of the specimens with varying Si content. Figure 8a encompasses the 2θ range of 30° to 90°, with peaks labeled by Miller indices as peak 110, 200, and 211 which correspond to the planes of the body-centered cubic (BCC) structure. The 2θ range of 43.6° to 45.4° focuses on the plane peak 110 (ref. Fig. 8b). The peak’s pattern among the specimens demonstrates a consistent BCC structure. However, the slight shifts in peak positions indicate lattice structure variations due to the different Si contents. These shifts suggest that the varying amounts of Si influences the crystallographic properties of the alloys. Notably, the peak shifting of specimens with 8.00 wt.% Si suggests that the BCC structure is predominantly directed by FeCrSi rather than by FeCrAl alloys.

Figure 9 presents a correlation between the Si content in FeCrAl specimens and their Vickers hardness (HV). The addition of 0.25 wt.% Si resulted in a slight decrease in the mean Vickers hardness compared to the specimen without Si. Although the decrement is observably far from the regression line, it still falls within the root mean square error of the regression, suggesting that the indicated mean may still approach the true value. Based on the data, there is a clear trend that the Si content increases the Vickers hardness values.

4. Discussion

Through this study, valuable insights were gained on the effects of Si solute in FeCrAl alloys. The implementation of FeCrAl alloys as a cladding material presents a neutron absorption issue, which is higher compared to the one using Zr-4 cladding, due to the higher neutron absorption of Fe by 3.8 times compared to Zr at thermal energy. The addition of Si, which also reduces the Fe content, decreases the overall neutron absorption cross-section of the cladding material. This reduction is beneficial in restoring the neutron economy, which is vital for an optimal fuel utilization and for a longer reactor operation. However, with the same size of fuel cladding, the kinf of this FeCrAl+Si systems are still far lower than the one using Zr-4 material. This suggests the FeCrAl+Si cladding system must be thinner than the existing Zr-4 cladding system to restore the kinf. A previous study conducted revealed that FeCrAl exhibits approximately twice the mechanical strength of zircaloy [40]. This suggests that the restoration of kinf can be done by reducing the cladding’s thickness.

This study also found that the microstructure and mechanical properties of FeCrAl alloys are enhanced by the addition of Si explainable in several physical phenomena. During solidification, Si atoms tend to segregate at grain boundaries, creating a barrier that hinders grain growth. This process, known as grain boundary pinning [41], prevents the movement of grain boundaries and facilitates the formation of smaller grains, resulting in a finer microstructure. The reduction in grain size directly influences the hardness of the alloy according to the Hall–Petch relationship [42]. This relationship established an opposite correlation between smaller grain sizes and higher hardness. This is due to the grain boundaries acting as obstacles for any dislocating movement. With more grain boundaries present in a finer-grained material, the dislocations encounter greater resistance, thereby enhancing the material’s hardness. Additionally, Si in the alloys can also contribute to solid solution strengthening [43]. Si atoms in the FeCrAl matrix may cause lattice distortions due to their differing atomic sizes compared to Fe, Cr, and Al. These distortions make the dislocation movement becomes more challenging, which further enhances the alloy’s hardness. These observations from previous studies are our particular interest to further investigate our synthesized materials in terms of their microstructure and mechanical properties.

5. Conclusion

This study systematically investigated the influence of Si additions (0–8.00 wt.%) on the neutron performance and microstructural properties of FeCrAl alloys suitable for ATF applications. Monte Carlo simulations confirmed that FeCrAl cladding imposes a significant neutronic penalty compared to Zr-4, reducing discharge time from ∼1160 to ∼830 days. Incorporating Si partially mitigates this effect, with 8.00 wt.% Si extending discharge by ∼20 days, though values remain below those of Zr-4. Experimentally, Si addition refined the grain size from ∼498 μm (0 wt.% Si) to ∼201 μm (8.00 wt.% Si) and increased hardness from ∼280 HV to ∼520 HV. These improvements are attributed to grain boundary pinning, Hall–Petch strengthening, and solid solution effects, supported by XRD lattice shifts and SEM/EDS observations. The findings highlight a clear trade-off: Si enhances microstructural stability and mechanical robustness but only partially offsets the neutronic penalty of FeCrAl. A promising pathway is to combine Si-modified FeCrAl alloys with reduced cladding thickness, leveraging their superior strength to restore neutronic efficiency while maintaining safety margins.

Funding

This study was partially supported by Research and Innovation Funding Program for Advanced Indonesia (RIIM) batch 3 Number B-848/II.7.5/FR.06/5/2023 and B-1031/III.2/FR.06.00/5/2023; and ORTN BRIN Project, HITN (Hasil Inovasi Teknologi Nuklir).

Conflicts of interest

The authors unequivocally state that there exists no conflict of interest that could potentially influence the outcomes of this study.

Data availability statement

The raw data from this study are available upon request. Please contact the corresponding author if you are interested in obtaining them.

Author contribution statement

This manuscript was collaboratively written by all authors. Conceptualization, Methodology, Writing – Original Draft Preparation, Visualization and Funding Acquisition, I Wayan Ngarayana; Software, Validation and Writing – Review & Editing, Dany Mulyana; Investigation, Writing – Review & Editing, and Data Curation, Andryansyah, Safiya Djuliana, Elfrida Saragi, Damianus Toersiwi Sony Tjahyani, Parikin Farihin & Almira Citra Amelia. All authors have read and approved the final version of the manuscript.

Acknowledgments

We extend our sincere gratitude to all members of the Nuclear Reactor Structural Integrity and Advanced Materials Laboratory at the Research Center for Nuclear Reactor Technology for their invaluable contributions to the in-depth discussion and technical enhancement of this manuscript.

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Cite this article as: I. Wayan Ngarayana, Dany Mulyana, Andryansyah, Elfrida Saragi, Damianus Toersiwi Sony Tjahyani, Almira Citra Amelia, Parikin Farihin, Safiya Djuliana. Impact of silicon on neutronic performance and microstructural evolution of FeCrAl alloys for ATF cladding, EPJ Nuclear Sci. Technol. 12, 21 (2026). https://doi.org/10.1051/epjn/2026013

All Tables

Table 1.

Composition of synthesized FeCrAl specimens. Cr and Al are maintained at 12.50 wt.%, and 4.50 wt.%, respectively. Si content varies between 0 and 8.00 wt.%, while Fe constitutes the remaining composition.

In the text

All Figures

Thumbnail: Fig. 1. Refer to the following caption and surrounding text. Fig. 1.

A typical assembly of a pressurized water reactor used in the Monte Carlo simulations. Unit is centimeters.
In the text
Thumbnail: Fig. 2. Refer to the following caption and surrounding text. Fig. 2.

The furnace was operated with an argon flow rate of approximately 10 ml/min. The temperature was gradually increased from room temperature to 660 °C for one hour, then maintained at that temperature for three hours. Subsequently, the temperature was raised to 900 °C for another hour and held for six hours. This process was repeated, with the temperature increasing to 1100 °C for one hour and held for three hours. Finally, the furnace was allowed to cool down to room temperature at a controlled rate.
In the text
Thumbnail: Fig. 3. Refer to the following caption and surrounding text. Fig. 3.

Infinite neutron multiplication factor of the assembly models with various cladding sub-system. In comparison to the Zr-4 system, the FeCrAl cladding system generally exhibits a significantly lower kinf. Notably, the incorporation of Si as solute element into FeCrAl leads to a modest increase in the kinf. This is due to the reduction in Fe content.
In the text
Thumbnail: Fig. 4. Refer to the following caption and surrounding text. Fig. 4.

The density of specimens varies depending on the Si content. Specimens with higher Si content exhibit lower density, which can be attributed to the low density of Si. Theoretical density calculated based on the fraction of pure elements is typically within the measurement uncertainty range.
In the text
Thumbnail: Fig. 5. Refer to the following caption and surrounding text. Fig. 5.

Optical microscope images of synthesized FeCrAl specimens: (a) without Si, (b) with 0.25 wt.% Si, (c) 0.50 wt.% Si, (d) 1.00 wt.% Si, (e) 2.00 wt.% Si, (f) 4.00 wt.% Si, and (g) 8.00 wt.% Si. As the Si content increases, the grain size in the specimens decreases.
In the text
Thumbnail: Fig. 6. Refer to the following caption and surrounding text. Fig. 6.

Grain size distribution of FeCrAl specimens: (a) without Si, (b) with 0.25 wt.% Si, (c) 0.50 wt.% Si, (d) 1.00 wt.% Si, (e) 2.00 wt.% Si, (f) 4.00 wt.% Si, and (g) 8.00 wt.% Si. Specimens with higher Si content exhibit smaller grain sizes.
In the text
Thumbnail: Fig. 7. Refer to the following caption and surrounding text. Fig. 7.

SEM/EDS observation of synthesized FeCrAl specimens after etching at 2000 times magnification: (a) without Si, (b) with 0.25 wt.% Si, (c) 0.50 wt.% Si, (d) 1.00 wt.% Si, (e) 2.00 wt.% Si, (f) 4.00 wt.% Si, and (g) 8.00 wt.% Si. Well-defined grains are discernible from all specimens. EDS analysis reveals the relatively uniform distribution of all elements. Notably, in the specimen devoid of Si, surface is very coarse. As the concentration of Si increases, the coarseness of the surface decrease accordingly.
In the text
Thumbnail: Fig. 8. Refer to the following caption and surrounding text. Fig. 8.

XRD analysis of FeCrAl specimens with varying Si content (a) from 2θ = 30° to 90° and (b) zoomed in at 2θ = 43.6° to 45.4° reveals a consistent BCC structure. However, peaks shifting rightward suggest lattice structure changes due to the addition of Si solute.
In the text
Thumbnail: Fig. 9. Refer to the following caption and surrounding text. Fig. 9.

Impact of Si content on the Vickers hardness of FeCrAl specimens. As the Si content increases, the Vickers hardness values also increase linearly.
In the text

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