DEENP - Departamento de Engenharia de Produção

URI permanente desta comunidadehttp://www.hml.repositorio.ufop.br/handle/123456789/556

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2020 - 20212

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Autor: search.filters.author.Barros, André dos SantosAssunto: search.filters.subject.Solidification

Resultados da Pesquisa

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    Corrosion behavior of an AleSneZn alloy : effects of solidification microstructure characteristics.
    (2021) Barros, André dos Santos; Cruz, Clarissa Barros da; Garcia, Amauri; Cheung, Noé
    Due to its strong influence on service life of manufactured parts, corrosion resistance is an important factor to consider when designing Al alloys for engineering applications. With this in mind, the present study focuses on understanding the role of microstructure features in the corrosion behavior of an Al-10wt.%Sn-5wt.%Zn alloy. Samples with different microstructural length scales were subjected to corrosion tests, which were performed using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. An equivalent circuit analysis was also carried out. The results revealed a relatively high electrochemical activity of the studied alloy. Furthermore, coarsening in microstructure showed a slight tendency towards improvements in the corrosion resistance, that is, coarser microstructures composed by Al-rich dendrites surrounded by SneZn constituent particles were comparatively less prone to corrosion degradation than finer ones. Finally, the proposed equivalent circuit model is shown to have good agreement with the experimental EIS measurements.
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    Plate-like growth in a eutectic Bi–Ni alloy : effects of morphological microstructure evolution and Bi3Ni intermetallic phase on tensile properties.
    (2020) Cruz, Clarissa Barros da; Lima, Thiago Soares; Kakitani, Rafael; Barros, André dos Santos; Garcia, Amauri; Cheung, Noé
    The development of efficient thermal interface materials (TIMs) has become an emerging demand mainly driven by the continual rise in power dissipation of high-performance microprocessors. In this context, Bi-based alloys are among the promising types of TIMs for electronic packaging applications. However, the influence of the microstructural arrangement on mechanical strength of Bi–Ni alloys remains barely understood. To overcome this issue, this study aims to develop quantitative microstructure features-tensile properties correlations for a Bi–0.28 wt.%Ni alloy solidified in a wide range of cooling rates (T). ̇ In addition to the phase diagram calculated by the Thermo-Calc software (SSOL6 database) and differential scanning calorimetry analysis, the characterization of the Bi3Ni intermetallic compound is carried out using X-ray diffraction and SEM microscopy with energy disper- sive X-ray spectroscopy. Wavy instabilities in the plate-like morphology of the Bi matrix are shown to occur for T ̇ ≤ 0.13 ◦C/s. Besides that, more significant variations in yield and ultimate tensile strengths, y and u, respectively, are associated with a certain range of microstructural spacings between Bi plates () from 47.6 to 135.2m. Hence, Hall–Petch type relations are proposed to describe the variation of both y and u as a function of .