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FeCrAl alloys are under development as possible candidate materials of accident-tolerant fuel cladding in light water reactors. In this study, the cracking resistance of FeCrAl alloys was evaluated using half-size Charpy impact tests at temperatures ranging from room temperature to 600 °C. Ingot-metallurgy wrought FeCrAl alloys with base alloy compositions of Fe-(10–13)Cr-6Al-2Mo, in weight percent, and commercial powder-metallurgy FeCrAl alloys (Kanthal APMT) were investigated. All studied alloys showed almost zero absorbed impact energy at room temperature with brittle fracture behavior. The as-received APMT alloys exhibited poor impact toughness even at 600 °C. The ductile-brittle transition temperatures of the wrought FeCrAl alloys varied from 119 to 318 °C. The possible effects of microstructures, residual strain, materials preparation methods, process conditions, and chemical composition on the impact toughness of FeCrAl alloys were investigated by examining the Charpy impact data in combination with microstructural details of the alloys. [ABSTRACT FROM AUTHOR]

The processability of a Mo-containing FeCrAl alloy (Fe-13Cr-5.2Al-2Mo base, in wt%), developed for accident-tolerant nuclear fuel claddings, was evaluated through a stepwise rolling process at 400 °C under two different inter-pass annealing conditions (i.e., 650 °C for 1 h and at 870 °C for 30 min). The inter-pass annealing at 870 °C easily softened the FeCrAl alloy; however, it led to the formation of coarse grains of ~200 µm. On the other hand, the FeCrAl alloy maintained elongated, deformed grains with the inter-pass annealing at 650 °C, but the annealed samples showed relatively high deformation resistance and strong texture. Important aspects concerning the processability and microstructural control of FeCrAl alloys, such as deformation inhomogeneity, texture development, and grain coarsening, were discussed. Optimized processing conditions were recommended, based on the results, to achieve desirable microstructures with balanced processability and mechanical properties. [ABSTRACT FROM AUTHOR]

To develop the next generation of accident-tolerant fuel cladding for light-water nuclear reactors, wrought FeCrAlY alloys with varying amounts of Cr and Al and commercial Kanthal APMT alloy were evaluated for short-term (4 h) oxidation resistance in steam and air at 1200-1475 °C. Model alloys with lower Cr contents and higher Al contents were evaluated as lower Cr contents are desirable for radiation damage resistance during operation. As expected, a synergistic effect was found between the Cr and Al contents to enable protective AlO formation under these conditions. Characterization of the alumina scales formed in steam found that the scale morphology was affected by the alloy Y content and detailed scanning transmission electron microscopy (STEM) detected Y segregation along scale grain boundaries at 1200 °C. However, after 4 h at 1475 °C, Y and Hf were not segregated to the oxide grain boundaries formed on APMT and the scale had a single layer structure. Compared to oxidation in air, STEM characterization of the outer scale showed differences in the Fe and Cr distributions in steam. Graphical Abstract: [ABSTRACT FROM AUTHOR]

The stability of coherent L12-ordered Ni3(Al,Ti) intermetallic precipitates was studied in Fe–14Cr–32Ni–3Nb–(3–4)Al–(1–3)Ti (wt.%) based alumina-forming austenitic stainless alloys. Computational thermodynamics predicted the formation of multi-intermetallic phases, including L12 and β-NiAl (B2), in an austenite matrix below ∼900°C. Microstructure characterization revealed a significant stabilization of the L12 phase by Zr addition, with the amount of L12 increasing with increasing Ti addition. However, the Ti addition also degraded the oxidation resistance. Further additions of C and B successfully improved both creep and oxidation properties. [ABSTRACT FROM AUTHOR]

Geastrum berkeleyi, G. fornicatum, and G. minimum are newly recorded from Japan. A peristome of G. fornicatum has hitherto been described as indistinct, whereas the Japanese specimens have a well-delimited, fibrillose peristome. Geastrum minus, reported for the first time from Japan by Sanshi Imai, represents G. quadrifidum. Macroscopic and microscopic features of those four taxa are described and illustrated based on Japanese specimens. [ABSTRACT FROM AUTHOR]

Abstract: Two new bisindole alkaloids, 6-hydroxystaurosporinone (1) and 5,6-dihydroxyarcyriaflavin A (2) were isolated from field-collected fruit bodies of a myxomycete Lycogala epidendrum, along with eight known bisindoles (3–10). The structures of these new compounds were determined on the basis of spectroscopic data. Compounds 1 and 2 showed cytotoxicity against HeLa, Jurkat, and vincristine resistant KB/VJ300 cells, and compound 1, particularly, inhibited protein tyrosine kinase activity. [Copyright &y& Elsevier]

The microstructures and mechanical properties of deformed and annealed Nb-containing FeCrAl alloys were investigated. Fine dispersion of Fe 2 Nb-type Laves phase particles was observed in the bcc-Fe matrix after applying a thermomechanical treatment, especially along grain/subgrain boundaries, which effectively stabilized the recovered and recrystallized microstructures compared with the Nb-free FeCrAl alloy. The stability of recovered areas increased with Nb content up to 1 wt%. The recrystallized grain structure in Nb-containing FeCrAl alloys consisted of elongated grains along the rolling direction with a weak texture when annealed below 1100 °C. An abnormal relationship between recrystallized grain size and annealing temperature was found. Microstructural inhomogeneity in the deformed and annealed states was explained based on the Taylor factor. Annealed Nb-containing FeCrAl alloys showed a good combination of strength and ductility, which is desirable for their application as fuel cladding in light-water reactors. [ABSTRACT FROM AUTHOR]

The effects of Mo and Nb additions on the microstructure and mechanical properties of two FeCrAl alloys were studied. Fine and uniform recrystallized grain structures (~ 20–30 μm) were achieved in both alloys through suitable annealing after warm-rolling. The formation of Fe 2 Nb-type Laves phase precipitates in the Nb-containing FeCrAl alloy effectively stabilized the deformed and recrystallized microstructures. The Mo-containing FeCrAl alloy exhibited strong γ texture fiber after annealing at 650–900 °C, whereas the annealed Nb-containing FeCrAl alloy had much weaker texture. Both strength and ductility decreased as the grain size increased in both alloys. [ABSTRACT FROM AUTHOR]

Post–neutron irradiation examination is performed on advanced accident-tolerant fuel (ATF) cladding iron-chromium-aluminum (FeCrAl) alloys with ∼10–13at. % Cr, ∼10–12 at. % Al, ∼1 at. % Mo, and minor alloying elements including Y irradiated to a damage level of 7 displacements per atom (dpa) at irradiation temperatures of 267–282 °C. A compositional dependency of the Cr and Al content is observed on the ratio of sessile and glissile dislocation loops, where the density of a ⟨100⟩ type loops is somewhat higher than the a /2⟨111⟩ type loops. The α ′ precipitate number density is inversely correlated to the starting Cr concentration of the alloys of interest. The irradiation to a higher dose of 7 dpa results in a higher density of dislocation loops and α ′ precipitates for the same alloys at a lower irradiation dose, such as 1.8 dpa. In this work, the effect of α ′ precipitates on the dislocation loop density is discussed, and the presence of α ′ appears to inhibit the nucleation of loops. Compared with first-generation FeCrAl alloys, these advanced alloys with heterogeneous structure exhibit a lower Cr concentration in α ′ precipitation at the same dose level; they act as weaker obstacles deviating from the primary hardening contribution from the mature α ′. Hence, the overall irradiation-induced hardening decreases; our alloys show improved radiation resistance because of their stronger sink strengths. The results presented in this paper could provide insights for the design and optimization of ATF cladding materials for future fission and space applications. [Display omitted] [ABSTRACT FROM AUTHOR]

Ferritic-structured Fe–Cr–Al alloys are being developed and show promise as oxidation resistant accident tolerant light water reactor fuel cladding. This study focuses on investigating the weldability and post-weld mechanical behavior of three model alloys in a range of Fe–(13–17.5)Cr–(3–4.4)Al (wt.%) with a minor addition of yttrium using modern laser-welding techniques. A detailed study on the mechanical performance of bead-on-plate welds using sub-sized, flat dog-bone tensile specimens and digital image correlation (DIC) has been carried out to determine the performance of welds as a function of alloy composition. Results indicated a reduction in the yield strength within the fusion zone compared to the base metal. Yield strength reduction was found to be primarily constrained to the fusion zone due to grain coarsening with a less severe reduction in the heat affected zone. For all proposed alloys, laser welding resulted in a defect free weld devoid of cracking or inclusions. [ABSTRACT FROM AUTHOR]

A widespread implementation of large scale additive manufacturing (AM) processes, such as wire arc-directed energy deposition (WA-DED) AM can transform the current manufacturing supply chain networks. Naturally, such implementation requires control of the microstructural attributes, such as texture and phase evolution in the processed alloys. Currently, the texture evolution in fusion-based AM (F-BAM) processes is majorly rationalized by the phenomena occurring only during solidification. However, such rationalization is insufficient for understanding the evolution of primary and secondary crystallographic orientations, and consequently, fails to offer a comprehensive understanding and control of overall texture in F-BAM processed alloys. To this end, we report a single crystal (SX)-like texture in WA-DED processed SS316L for the first time. Furthermore, we assess the physical phenomena that may lead to such unique microstructural evolution during WA-DED AM. Subsequently, using microstructural characterization spanning the build height and thermomechanical simulations we investigate the effect of competitive growth and epitaxial growth occurring during solidification and thermally induced plastic deformation occurring post solidification on the overall texture of WA-DED processed SS316L. A spatial variation in solidification pathway is also established and correlated with variation in undercoolings across the build. Tensile tests revealed a strong orientation dependence of deformation mechanisms with over 110% elongation to failure of specimens deformed along <011>. Such anisotropy is rationalized using Schmid's analysis of dislocation slip and deformation twinning. Overall, the mechanisms outlined in this work will facilitate an enhanced understanding and subsequent control of texture evolution, solidification behavior and mechanical behavior of WA-DED processed steels. [Display omitted] • A SX-like texture is reported in a directed energy deposition processed SS316L. • Phenomena occurring during and post solidification affect texture in DED. • Tip temperatures of γ and δ phases and solidification modes vary with build height. • Stray-grain formation is rationalized using spatially varying thermokinetics. • Orientation dependent behavior of leading/trailing partials leads to anisotropy. [ABSTRACT FROM AUTHOR]

A corrosion- and creep-resistant austenitic stainless steel has been developed for advanced recuperator applications. By optimizing the AI and Cr contents, the alloy is fully austenitic for creep strength while allowing the formation of a chemically stable external alumina scale at temperatures up to 900°C. An alumina scale eliminates long-term problems with the formation of volatile Cr oxy-hydroxides in the presence of water vapor in exhaust gas. As a first step in producing foil for primary surface recuperators, three commercially cast heats have been rolled to ~100 µm thick foil in the laboratory to evaluate performance in creep and oxidation testing. Results from initial creep testing are presented at 675 °C and 750 °C, showing excellent creep strength compared with other candidate foil materials. Laboratory, exposures in humid air at 650-800°C have shown acceptable oxidation resistance. A similar oxidation behavior was observed for sheet specimens of these alloys exposed in a modified 65 kW microturbine for 2871 h. One composition that showed superior creep and oxidation resistance has been selected for the preparation of a commercial batch of foil. [ABSTRACT FROM AUTHOR]

Abstract: Three kinds of cyclodextrin (CD) dimer (one homo-dimer of β-CD and two types of hetero-dimer of α-CD and β-CD) were synthesized as artificial hydrolases. The initial rates of the cleavage reaction of p-nitrophenyl methoxyethoxyethoxyacetate (8) by each of the three dimers were measured under the condition of excess of substrate at 25°C in a pH 7.4 phosphate buffer solution. In a plot of initial rate against concentration of the substrate, the reaction with the homo-dimer (βCβH 5) gave a sigmoidal curve, whereas the reaction with either of the hetero-dimers gave a simple hyperbolic curve. Only βCβH 5 showed homotropic cooperativity, with a Hill constant of 1.8. [Copyright &y& Elsevier]

Arcyria monticola was found in Hokkaido, northern Japan. This is the first record of its locality, except for the type locality. The linearly expanding capillitium with many coils characterizing A. monticola consists of very elastic longitudinal tubes, short lateral tubes, and many small intricate nets. A longitudinal tube coils around a small intricate net, which forms a core. In contrast, A. imperialis, the other known Arcyria species with a linearly expanding capillitium, has neither short lateral tubes nor nets. The microscopic character of the A. imperialis capillitium is also totally different from that of A. monticola. [ABSTRACT FROM AUTHOR]

Abstract: Kehokorins A ( 1 )–C ( 3 ), three novel dibenzofurans, have been isolated from field-collected fruit bodies of the myxomycete, Trichia favoginea var. persimilis, and their structures were elucidated by spectral data. Kehokorin A ( 1 ) was a α-l-rhamnopyranoside of kehokorin B ( 2 ), while kehokorin C ( 3 ) was a 1-demethoxy analog of 2 . Kehokorin A ( 1 ) was cytotoxic against HeLa cells with an IC50 value of 1.5μg/mL. [Copyright &y& Elsevier]

The chromium (Cr) evaporation behavior of several different types of iron (Fe)-based AFA alloys and benchmark Cr 2 O 3 -forming Fe-based 310 and Ni-based 625 alloys was investigated for 500 h exposures at 800 °C to 900 °C in air with 10% H 2 O. The Cr evaporation rates from alumina-forming austenitic (AFA) alloys were ~5 to 35 times lower than that of the Cr 2 O 3 -forming alloys depending on alloy and temperature. The Cr evaporation behavior was correlated with extensive characterization of the chemistry and microstructure of the oxide scales, which also revealed a degree of quartz tube Si contamination during the test. Long-term oxidation kinetics were also assessed at 800 to 1000 °C for up to 10,000 h in air with 10% H 2 O to provide further guidance for SOFC BOP component alloy selection. • Cr evaporation and oxidation behaviors of AFA alloys were studied. • Cr evaporation rates from AFA alloys were much lower than chromia-forming alloys. • Continuous alumina layer formed on AFA alloys remained steady after test. • Possible Si contamination and Cr deposited on alumina tubes were discussed. [ABSTRACT FROM AUTHOR]

Castable alumina forming austenitic (AFA) alloys have demonstrated superior creep life and oxidation resistance at temperatures exceeding 800⁰C. Despite the success in the applicability of these alloys in extreme environments, there is a limited understanding of the deformation modes and the influence of each alloying element guiding the alloy design strategies that could further enhance the creep strength of these AFA alloys, particularly at temperatures at and above 900⁰C. In this study, we reveal the mechanism underpinning the superior creep performance of castable AFA alloys that involves suppressing primary carbide formation through minor compositional modification. This approach results in a three-fold increase in creep strength at 900⁰C and 50 MPa. By employing integrated characterization techniques, we analyzed the microstructures of two AFA alloys, both before and after the creep process. We discovered that the suppression of primary carbides permits the in-situ clustering of now-available interstitial elements such as C, Si, and O during high-temperature creep. This improved solid solution strengthening and reduced stacking fault energy of the alloy. Moreover, it also enabled controlled secondary carbide formation during testing, further improving the creep resistance. These findings underline the important interplay between alloy composition, microstructure, and creep properties, and offer a promising design strategy for developing economical high-temperature Fe-based alloys suitable for advanced applications. [Display omitted] [ABSTRACT FROM AUTHOR]

From a myxomycete Arcyria ferruginea, dihydroarcyriarubin C (1), a new bisindole alkaloid, has been isolated together with two known bisindoles, arcyriarubin C (2) and arcyriaflavin C (3), and arcyriaflavin C (3) was also isolated from Tubifera casparyi together with arcyriaflavin B (4). Arcyriaflavin C (3) exhibited cell cycle inhibition effect at G1 and G2/M stage at 10 and 100 ng/mL, respectively. [Copyright &y& Elsevier]

• Mechanical properties of ten steel variants were compared with reference Eurofer97. • Miniature multi-notch bend bars were used for transition fracture toughness testing. • No comprehensive mechanical property improvement was found from ten variants. • Structural-property correlation was discussed for selected variants. Under the framework of EUROfusion, we performed comprehensive mechanical and microstructure characterization of ten Eurofer97 steel variants with varying compositions and heat treatment conditions. We characterized the pre-irradiation fracture toughness of the materials along with their Vickers hardness, tensile properties, and microstructure. Compared with standard Eurofer97, the ten variants didn't show a comprehensive improvement of mechanical properties. In addition, the composition and microstructures in some variants are adverse to fracture toughness, such as low C contents, coarse grain sizes, partially tempered martensite, lack of precipitates, and non-uniform distributions of coarse precipitates. Further studies will be performed on the same materials after neutron irradiation. [ABSTRACT FROM AUTHOR]

A recent investigation has confirmed that solute atoms segregated to the interfaces between aluminum and θ ′-Al 2 Cu can extend the stability of metastable θ ′ to higher temperatures. Herein, we present an extensive first-principles database of the segregation energies of 34 elements to the Al/ θ ′ interface and identify key descriptors that can guide the design of higher temperature Al-Cu alloys. We find that the segregation energies are strongly correlated with the size and volume of solute atoms and their solubilities within θ ′. We provide a physical/chemical basis to the experimentally observed elemental hierarchy in terms of the ability of individual elements to stabilize the Al/ θ ′ interface. Finally, we suggest a new microalloying strategy that offers opportunities to further increase the critical temperature limit of Al-Cu alloys. [ABSTRACT FROM AUTHOR]

FeCrAl alloys with varying compositions and microstructures are under consideration for accident-tolerant fuel cladding, but limited details exist on dislocation loop formation and growth for this class of alloys under neutron irradiation. Four model FeCrAl alloys with chromium contents ranging from 10.01 to 17.51 wt % and aluminum contents of 4.78 to 2.93 wt % were neutron irradiated to doses of 0.3–0.8 displacements per atom (dpa) at temperatures of 335–355 °C. On-zone STEM imaging revealed a mixed population of black dots and larger dislocation loops with either a / 2 〈 111 〉 or a 〈 100 〉 Burgers vectors. Weak composition dependencies were observed and varied depending on whether the defect size, number density, or ratio of defect types was of interest. Results were found to mirror those of previous studies on FeCrAl and FeCr alloys irradiated under similar conditions, although distinct differences exist. [ABSTRACT FROM AUTHOR]

The development and understanding of the mechanical properties of neutron-irradiated FeCrAl alloys is increasingly a critical need as these alloys continue to become more mature for nuclear reactor applications. This study focuses on the mechanical properties of model FeCrAl alloys and of a commercial FeCrAl alloy neutron-irradiated to up to 13.8 displacements per atom (dpa) at irradiation temperatures between 320 and 382 °C. Tensile tests were completed at room temperature and at 320 °C, and a subset of fractured tensile specimens was examined by scanning electron microscopy. Results showed typical radiation hardening and embrittlement indicative of high chromium ferritic alloys with strong chromium composition dependencies at lower doses. At and above 7.0 dpa, the mechanical properties saturated for both the commercial and model FeCrAl alloys, although brittle cleavage fracture was observed at the highest dose in the model FeCrAl alloy with the highest chromium content (18 wt %). The results suggest the composition and microstructure of FeCrAl alloys plays a critical role in the mechanical response of FeCrAl alloys irradiated near temperatures relevant to light water reactors. [ABSTRACT FROM AUTHOR]

FeCrAl alloys are currently under consideration for accident-tolerant fuel cladding applications in light water reactors owing to their superior high-temperature oxidation and corrosion resistance compared to the Zr-based alloys currently employed. However, their performance could be limited by precipitation of a Cr-rich α ′ phase that tends to embrittle high-Cr ferritic Fe-based alloys. In this study, four FeCrAl model alloys with 10–18 at.% Cr and 5.8–9.3 at.% Al were neutron-irradiated to nominal damage doses up to 7.0 displacements per atom at a target temperature of 320 °C. Small angle neutron scattering techniques were coupled with atom probe tomography to assess the composition and morphology of the resulting α ′ precipitates. It was demonstrated that Al additions partially destabilize the α ′ phase, generally resulting in precipitates with lower Cr contents when compared with binary Fe-Cr systems. The precipitate morphology evolution with dose exhibited a transient coarsening regime akin to previously observed behavior in aged Fe-Cr alloys. Similar behavior to predictions of the LSW/UOKV models suggests that α ′ precipitation in irradiated FeCrAl is a diffusion-limited process with coarsening mechanisms similar to those in thermally aged high-Cr ferritic alloys. [ABSTRACT FROM AUTHOR]

FeCrAl alloys are an attractive class of materials for nuclear power applications because of their increased environmental compatibility compared with more traditional nuclear materials. Preliminary studies into the radiation tolerance of FeCrAl alloys under accelerated neutron testing between 300 and 400 °C have shown post-irradiation microstructures containing dislocation loops and a Cr-rich α′ phase. Although these initial studies established the post-irradiation microstructures, there was little to no focus on understanding the influence of pre-irradiation microstructures on this response. In this study, a well-annealed commercial FeCrAl alloy, Alkrothal 720, was neutron irradiated to 1.8 displacements per atom (dpa) at 382 °C and then the effect of random high-angle grain boundaries on the spatial distribution and size of a 〈100〉 dislocation loops, a /2〈111〉 dislocation loops, and black dot damage was analyzed using on-zone scanning transmission electron microscopy. Results showed a clear heterogeneous dislocation loop formation with a /2〈111〉 dislocation loops showing an increased number density and size, black dot damage showing a significant number density decrease, and a 〈100〉 dislocation loops exhibiting an increased size in the vicinity of the grain boundary. These results suggest the importance of the pre-irradiation microstructure and, specifically, defect sink density spacing to the radiation tolerance of FeCrAl alloys. [ABSTRACT FROM AUTHOR]

Abstract: Fuligoic acid (1), a new yellow pigment with a chlorinated polyene–pyrone acid structure, was isolated from field-collected fruit bodies of the myxomycete Fuligo septica f. flava, and its structure was elucidated by spectral data, including its absolute configuration based on CD data. [Copyright &y& Elsevier]

The Fe–Cr–Al alloy system has the potential to form an important class of enhanced accident-tolerant cladding materials in the nuclear power industry owing to the alloy system's higher oxidation resistance in high-temperature steam environments compared with traditional zirconium-based alloys. However, radiation tolerance of Fe–Cr–Al alloys has not been fully established. In this study, a series of Fe–Cr–Al alloys with 10–18 wt % Cr and 2.9–4.9 wt % Al were neutron irradiated at 382 °C to 1.8 dpa to investigate the irradiation-induced microstructural and mechanical property evolution as a function of alloy composition. Dislocation loops with Burgers vector of a/2〈111〉 and a〈100〉 were detected and quantified. Results indicate precipitation of Cr-rich α′ is primarily dependent on the bulk chromium composition. Mechanical testing of sub-size-irradiated tensile specimens indicates the hardening response seen after irradiation is dependent on the bulk chromium composition. A structure–property relationship was developed; it indicated that the change in yield strength after irradiation is caused by the formation of these radiation-induced defects and is dominated by the large number density of Cr-rich α′ precipitates at sufficiently high chromium contents after irradiation. [ABSTRACT FROM AUTHOR]

Abstract: Foil and sheet forms of the nickel-based superalloy 625 have been examined in an ‘as-processed’ condition and following creep-rupture testing in air at 750°C and 100MPa. Both scanning and transmission electron microscopies were employed to correlate microstructures with creep behavior, and indicate the additional processing required to achieve foil form reduces creep life compared to thicker-section wrought product forms. Prior to creep testing, the microstructure consists of γ phase with M6C precipitates. This microstructure changes during creep into one consisting of orthorhombic δ phase extending across the γ grains, and grain boundaries dominated by the presence of rhombohedral μ phase, δ phase, and a Si-rich variant of diamond-cubic M6C (η phase). Thermodynamic modeling was also used to calculate the stable temperature ranges and compositions of equilibrium phases. The phases predicted by modeling and their compositions generally agree with those observed within alloy 625 after creep testing. [Copyright &y& Elsevier]

Abstract: Trichiol (1) and 3-epitrichiol acetate (2), two new sterols, have been isolated from field-collected fruit bodies of the myxomycete, Trichia favoginea var. persimilis, and their structures elucidated by spectral data. Trichiol (1) and 3-epitrichiol acetate (2) possess an unprecedented 2,6-dioxabicyclo[2.2.2]octan-3-one ring system. Trichiol (1) was cytotoxic against HeLa cells, while compound 2 proved to exhibit reversal effect against TNF-related apoptosis inducing ligand (TRAIL)-resistant Jurkat cell lines. [Copyright &y& Elsevier]

Abstract: Tubiferal A, a novel rearranged triterpenoid lactone, has been isolated from field-collected fruit bodies of the myxomycete, Tubifera dimorphotheca, and its structure elucidated by spectral data. Tubiferal A (1) possesses a 9,10-secocycloartan-16,21-olide skeleton, and this new compound exhibited a reversal effect of vincristine (VCR) resistance (more than 4-fold) against VCR-resistant KB cell lines. Tubiferal B (2), corresponding to the seco acid of 1 was also isolated, but showed no comparable activity. [Copyright &y& Elsevier]

FeCrAl alloys have been extensively investigated over the past decade as a candidate material for accident-tolerant fuel cladding in light water reactors. This work completes a first of its kind study where Al and Cr concentrations are varied systematically under neutron irradiation to elucidate the post irradiation microstructural and mechanical response as a direct result of alloying content. Neutron irradiations were performed on alloys with composition Fe-(10-13)Cr-(5-7)Al in wt.% at temperatures of 214, 357, and 557°C to a dose of ~1.8 dpa (displacements per atom). Dislocation loop sizes and dispersion characteristics did not show strong compositional dependence. However, there were noticeable effects of composition on the dispersion of Cr-rich α ′ -precipitates, particularly a decrease in number density with increasing Al content or a decrease in Cr content. The present results confirm previous studies indicating the Cr concentration in these precipitates is lower than that expected in binary FeCr alloys and that Al can act as a destabilizing alloying element for the deleterious α ′ -phase. [Display omitted] [ABSTRACT FROM AUTHOR]

As part of an effort to develop advanced fuel cladding for use in light water reactors, several FeCrAl alloys have been developed at Oak Ridge National Laboratory. A second generation of these alloys bearing additional alloying elements over the previously tested model alloys were tested in boiling water reactor (BWR) conditions to determine their resistance to hydrothermal corrosion. Coupons with alloy compositions Fe–10Cr–6Al–2Mo, Fe–13Cr–5Al–2Mo, Fe–13Cr–6Al–2Mo, Fe–13Cr–7Al–2Mo, and Fe–13Cr–5Al–2Mo–1Nb were tested in normal water chemistry (NWC) and hydrogen water chemistry (HWC) for 9 months in continuously refreshing autoclaves. Commercial FeCrAl alloy APMT and Zircaloy-2 were also tested for comparison. Among samples exposed to HWC, Fe–13Cr–7Al–2Mo performed worst with an average mass loss of 1.3 mg/cm2 over 9 months. This mass loss represents an estimated thickness loss of approximately 60 μm over 6 years. Samples exposed to NWC had very small mass losses of less than 0.15 mg/cm2 or mass gains up to 0.05 mg/cm2. Based on the results of this testing, the 2nd generation FeCrAl alloys tested exhibit low wall thickness loss and are suitable in terms of corrosion resistance for use as LWR cladding in BWR-HWC and BWR-NWC under normal operating conditions. [ABSTRACT FROM AUTHOR]

The Fe–Cr–Al–Nb ferritic alloys strengthened by A 2 B Laves phases, with superior oxidation and corrosion resistance, are being considered for high temperature operation within fossil-fired steam power plants to increase process efficiency and reduce CO 2 emissions. In this study, new sets of alloys based on Fe–30Cr–3Al–1Nb (in weight percent) were designed with (i) a high microstructural stability of Laves phase precipitates in a BCC-Fe matrix and (ii) reduced precipitate free zones along the grain boundaries, targeting an operating temperature of 700 °C. Two alloys with titanium or tungsten additions were down-selected through thermodynamic calculations with a design strategy to maximize the amount of Laves phase at 700 °C and lower the BCC solvus temperature. To validate this design strategy, the candidate alloys were cast, heat treated and aged at 700 °C, and the resulting microstructure was characterized using scanning electron microscopy and atom probe tomography. The alloys with titanium addition (1 wt%) showed monotonic precipitate coarsening. On the other hand, the alloys with tungsten addition (6 wt%) showed a reduced coarsening rate of Laves phase precipitates in the matrix up to 1008 h aging, whereas an acceleration of the precipitate coarsening after that. Atom probe tomography of this alloy revealed the formation of a core-shell precipitate structure with a Nb/Si rich core and W-rich shell, while the alloy with Ti-addition did not show the core-shell structure. The detailed characterization results revealed that the core-shell structure was strongly correlated with the observed two-step coarsening mode in the tungsten containing alloy. • A design strategy for creep-resistant Fe–Cr–Al–Nb based ferritic alloys via thermodynamic calculations was proposed. • The corresponding microstructural evolutions of the designed alloys were validated via electron microscopy. • A Nb/Si rich core and W-rich shell was observed in the alloy with W by atom probe tomography, but not in the alloy with Ti. • The core-shell structure was rationalized by the larger diffusivity difference between Nb and W, compared to Nb and Ti. [ABSTRACT FROM AUTHOR]