MARIANA XAVIER MILAGRE

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2018 - 201922020 - 20211
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Fator de Impacto: 3.000 - 4.499 × Autor: ISOLDA COSTA ×

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    Artigo IPEN-doc 27829
    Use of amperometric and potentiometric probes in scanning electrochemical microscopy for the spatially-resolved monitoring of severe localized corrosion sites on aluminum alloy 2098-T351
    2021 - SILVA, REJANE M.P. da; IZQUIERDO, JAVIER; MILAGRE, MARIANA X.; BETANCOR-ABREU, ABENCHARA M.; COSTA, ISOLDA; SOUTO, RICARDO M.
    Amperometric and potentiometric probes were employed for the detection and characterization of reactive sites on the 2098-T351 Al-alloy (AA2098-T351) using scanning electrochemical microscopy (SECM). Firstly, the probe of concept was performed on a model Mg-Al galvanic pair system using SECM in the amperometric and potentiometric operation modes, in order to address the responsiveness of the probes for the characterization of this galvanic pair system. Next, these sensing probes were employed to characterize the 2098-T351 alloy surface immersed in a saline aqueous solution at ambient temperature. The distribution of reactive sites and the local pH changes associated with severe localized corrosion (SLC) on the alloy surface were imaged and subsequently studied. Higher hydrogen evolution, lower oxygen depletion and acidification occurred at the SLC sites developed on the 2098-T351 Al-alloy.
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    Artigo IPEN-doc 25087
    Correlation between corrosion resistance, anodic hydrogen evolution and microhardness in friction stir weldment of AA2198 alloy
    2018 - DONATUS, UYIME; VIVEIROS, BARBARA V.G. de; ALENCAR, MAICON C. de; FERREIRA, RAPHAEL O.; MILAGRE, MARIANA X.; COSTA, ISOLDA
    Correlation between corrosion resistance, anodic hydrogen evolution and microhardness in the friction stir weldment of AA2198-T851 alloy has been investigated. Different microscopy techniques, scanning vibrating electrode technique (SVET) and potentiodynamic polarization tests were employed in the investigation. Unlike other 3rd generation Al-Cu-Li alloys where the regions that are most susceptible to corrosion are always within the weld region, the results reveal that the parent material is the most susceptible in this case. There is a direct correlation between corrosion resistance, anodic hydrogen evolution and microhardness in the weldment, and the T1 phase is associated with the direct correlation.
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    Artigo IPEN-doc 24759
    On the microstructure characterization of the AA2098-T351 alloy welded by FSW
    2018 - MILAGRE, MARIANA X.; MOGILI, NAGA V.; DONATUS, UYIME; GIORJAO, RAFAEL A.R.; TERADA, MAYSA; ARAUJO, JOAO V.S.; MACHADO, CARULINE S.C.; COSTA, ISOLDA
    The complex structure of the AA2098-T351 alloy welded by friction stir welding (FSW) was investigated by transmission electron microscopy (TEM), differential scanning calorimetry (DSC) and microhardness measurements. Thermal modelling process of the FSW process was carried out by soldering thermocouples at distances of 6, 9 and 12 mm from the weld centerline, and thermocouple measurements were used as input data into the model. Finite element software COMSOL v5.2 was used for data analysis. The prevailing phases in the base metal (BM) are T1 (Al2CuLi) theta' (Al2Cu), delta'/beta'(Al-3(Li,Zr)) and Omega (Al2Cu). In the heat affected zone (HAZ), either in the retreating or advancing sides, theta' phase was not identified. In the thermomechanical affected zone (TMAZ), T1, delta'/beta', GP zones phase were detected in the retreating side, whereas T1 and Guinier-Preston (GP) zones were not observed in the advancing side. This result supports the asymmetric behavior observed in the microhardness profile of the weld. In the stir zone (SZ), GP zones, T1, delta'/beta' (Al-3(Li,Zr)) and Omega were identified.