arXiv subjects

A. Zaborowska

Publications and source records attributed to A. Zaborowska.

7 recordsLinked to original sources

arXiv2026

High-temperature behavior of amorphous alumina coatings: Insights from in-situ nanoindentation and X-ray diffraction studies

Further development of nuclear power plant technology relies heavily on materials durability under operating conditions. Estimating the materials performance in the operando tests is crucial. In this paper, the mechanical behavior of thin amorphous nuclear-dedicated Al2O3 coatings deposited by pulsed laser deposition was investigated by nanoindentation over the temperature range of 25-650C. Experimental nanomechanical analysis was supported by MD simulations. The results indicate that the hardness of the amorphous coating experiences a gradual, constant decrease with temperature, while the Young modulus value remains constant in the whole temperature range. Observed phenomena confirm the increasing plasticity of the material and it is postulated to be related to the bond-switching mechanism that accelerates at high temperatures. The post-mortem transmission electron microscopy characterization confirmed that the loaded material was non-crystalline over the entire range of the indentation temperatures. The thermal stability of the structure was further studied in-situ up to 1050C by X-ray diffraction. The implemented methodology allowed us to follow the dynamic process of phase transitions occurring in the material above 650C. First, thermally activated crystallization was observed at 700C. Intermediate alumina phases were present up to 950C, while above this temperature, exclusively the thermodynamically stable alpha-Al2O3 was observed. The in-situ high-temperature characterization of the evolution of thin films boosts the understanding of the application limits of the coating systems at elevated temperatures. The added value is that the paper demonstrates the potential usefulness of combining high-temperature techniques to characterize the complete behavior of thin films at elevated temperatures.

cond-mat.mtrl-sci↗

arXiv2026

High-Temperature Deformation Behavior of Co-Free Non-Equiatomic CrMnFeNi Alloy

Cobalt-free high-entropy alloys (HEAs) have garnered interest for nuclear structural applications due to their good mechanical performance, thermal stability, and resistance to radiation-induced degradation, while avoiding long-lived Co radioisotopes. This study presents an experimental and computational investigation of the plastic deformation behavior of a non-equatomic CrMnFeNi alloy, designed to maintain a stability of fcc phase in a large domain of temperatures and to balance stacking fault (SF) energies for enhanced strain hardening and ductility. Tensile tests reveal a temperature-dependent reduction in mechanical strength, attributed to thermally activated deformation mechanisms and microstructural evolution. Molecular dynamics simulations of single- and polycrystals capture dislocation activity, SF formation, and twin nucleation as a function of strain and temperature. Electron backscatter diffraction (EBSD) confirms twin formation and grain boundary activity. The Schmid factor mapping is drawn to interpret local slip activity and anisotropic deformation behavior. The absence of Co leads to enhanced high-temperature strength compared to the Cantor alloy.

cond-mat.mtrl-sci↗

arXiv2025

The effects of high-temperature ion-irradiation on early-stage grain boundaries serrations formation in Ni-based alloys

Nickel based superalloys display outstanding properties such as excellent creep strength, remarkable fracture toughness parameters, and corrosion resistance. For this reason, Ni based materials are considered as materials dedicated to the IV generation of nuclear reactors. Although these materials seem promising candidates, their radiation resistance and impact of radiation damage on the deformation mechanism are still not fully understood. In this work, two commercially available nickel based alloys, Hastelloy X and Haynes 230, were investigated. Structural and mechanical properties have been described by means of SEM and EBSD, TEM, and nanoindentation tests. Radiation damage has been performed by Ar ion with energy 320keV with two doses up to 12dpa. Obtained results have revealed a hardening effect for both levels of damage. However, more intensive effects were observed for Hastelloy X. Moreover, a significant change in precipitates morphology in Hastelloy X has been observed. It has been proposed that structural differences between both alloys determine the type of occurring radiation induced processes. Excess energy deposited into materials structure during ion irradiation can lower the temperature of nucleation of high temperature phases, which initiates the formation of grain boundary serrations.

cond-mat.mtrl-sci↗

arXiv2023

Absolute radiation tolerance of amorphous alumina coatings at room temperature

In this study structural and mechanical properties of a 1 um thick Al2O3 coating, deposited on 316L stainless steel by Pulsed Laser Deposition (PLD), subjected to high energy ion irradiation were assessed. Mechanical properties of pristine and ion-modified specimens were investigated using the nanoindentation technique. A comprehensive characterization combining Transmission Electron Microscopy and Grazing-Incidence X-ray Diffraction provided deep insight into the structure of the tested material at the nano- and micro- scale. Variation in the local atomic ordering of the irradiated zone at different doses was investigated using a reduced distribution function analysis obtained from electron diffraction data. Findings from nanoindentation measurements revealed a slight reduction in hardness of all irradiated layers. At the same time TEM examination indicated that the irradiated layer remained amorphous over the whole dpa range. No evidence of crystallization, void formation or element segregation was observed up to the highest implanted dose. Reported mechanical and structural findings were critically compared with each other pointing to the conclusion that under given irradiation conditions, over the whole range of doses used, alumina coatings exhibit excellent radiation resistance. Obtained data strongly suggest that investigated material may be considered as a promising candidate for next-generation nuclear reactors, especially LFR-type, where high corrosion protection is one of the highest prerogatives to be met.

cond-mat.mtrl-sci↗

arXiv2023

High versus low energy ion irradiation impact on functional properties of PLD-grown alumina coatin

It is well known that ion irradiation can be successfully used to reproduce microstructural features triggered by neutron irradiation. Even though the irradiation process brings many benefits, it is also associated with several drawbacks. For example, the penetration depth of the ion in the material is very limited. This is particularly important for energies below MeV, ultimately reducing the number of available irradiation facilities. In addition to that, extracting information exclusively from the modified volume may be challenging. Therefore, extreme caution must be taken when interpreting obtained data. Our work aims to compare the findings of nanomechanical studies already conducted separately on thin amorphous ceramic coatings irradiated with ions of different energies, hence layers of different thicknesses. In this work, we show that in some instances, the 10% rule may be obeyed. In order to prove our finding, we compared results obtained for ion irradiated (with two energies: 0.25 and 1.2 MeV up to 25dpa) alumina coating system. Mechanical properties of pristine and ion-irradiated specimens were studied by nanoindentation technique. Interestingly, the qualitative relationship between nanohardness and irradiation damage level is very similar, regardless of the energy used. The presented work proves that for some materials (e.g., hard coatings), the qualitative assessment of the mechanical changes using nanoindentation might be feasible even for shallow implantation depths.

cond-mat.mtrl-sci↗

arXiv2023

Mechanical behavior of ion-irradiated ODS RAF steels strengthened with different types of refractory oxides

In the present work, authors focused on verifying structural and mechanical properties of Oxide Dispersed Strengthening (ODS) steels strengthened by three different types of refractory oxides submitted to ion-irradiation. Three materials strengthened with Y2O3 or Al2O3 or ZrO2 were produced by mechanical alloying and Spark Plasma Sintering technique. Specimens have been submitted to high energy Ar-ion irradiation at room temperature with three fluences. This procedure allowed to generate strongly damaged zone with a thickness of 230nm. SEM/EBSD and TEM observations, GIXRD analysis, and nanoindentation tests have been included in examination of modified layers. Investigation revealed alteration of structural and mechanical features as a result of Ar-irradiation. Obtained results showed a strong correlation between the strengthening oxide and materials' behavior under radiation damage. It has been proved that below 1x1015ions/cm2 mechanical properties in the modified layer of all materials are very similar. Reported behavior may be related to the efficient annealing of the radiation defect process. Above this limit, significant differences between the materials are visible. It is believed that described phenomenon is directly related to the presence of the structural features and their capacity to act as defect sinks. Consequently, type of dominant mechanisms occurring in modified layer is proposed.

cond-mat.mtrl-sci↗

arXiv2019

Calorimeters for the FCC-hh

The future proton-proton collider (FCC-hh) will deliver collisions at a center of mass energy up to $\sqrt{s}=100$ TeV at an unprecedented instantaneous luminosity of $L=3~10^{35}$ cm$^{-2}$s$^{-1}$, resulting in extremely challenging radiation and luminosity conditions. By delivering an integrated luminosity of few tens of ab$^{-1}$, the FCC-hh will provide an unrivalled discovery potential for new physics. Requiring high sensitivity for resonant searches at masses up to tens of TeV imposes strong constraints on the design of the calorimeters. Resonant searches in final states containing jets, taus and electrons require both excellent energy resolution at multi-TeV energies as well as outstanding ability to resolve highly collimated decay products resulting from extreme boosts. In addition, the FCC-hh provides the unique opportunity to precisely measure the Higgs self-coupling in the di-photon and b-jets channel. Excellent photon and jet energy resolution at low energies as well as excellent angular resolution for pion background rejection are required in this challenging environment. This report describes the calorimeter studies for a multi-purpose detector at the FCC-hh. The calorimeter active components consist of Liquid Argon, scintillating plastic tiles and Monolithic Active Pixel Sensors technologies. The technological choices, design considerations and achieved performances in full Geant4 simulations are discussed and presented. The simulation studies are focused on the evaluation of the concepts. Standalone studies under laboratory conditions as well as first tests in realistic FCC-hh environment, including pileup rejection capabilities by making use of fast signals and high granularity, have been performed. These studies have been performed within the context of the preparation of the FCC conceptual design reports (CDRs).

physics.ins-det↗