Navegando por Autor "Silva, Maria Adrina Paixão de Souza da"

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Dry sliding wear features of an Al-20Sn-5Zn alloy affected by microstructural length scales.
(2022) Cota, André Barros; Cruz, Clarissa Barros da; Botelho, Tamires; Silva, Maria Adrina Paixão de Souza da; Casteletti, Luiz Carlos; Garcia, Amauri; Cheung, Noé
Al-Sn-Zn alloys are attractive options for use as wear-resistant materials. While Sn promotes self-lubricating characteristics, Zn strengthens the Al-rich matrix. Conventionally, the manufacturing of these alloys involves casting. However, there is still a paucity of studies that associate the solidification microstructure with the wear resistance of these alloys. Inspired by such considerations, this work aims at investigating the wear behavior of an Al-20Sn-5Zn [wt.%] alloy produced by a directional solidification technique. A set of samples with different microstructure length scales was subjected to ball cratering tests using a normal contact load of 0.25 N and six test times. The results show that the dependence of the wear behavior on the microstructure length scale becomes more expressive for longer sliding distances. It was found that coarser microstructures provide an improved wear resistance. In view of that, a possible spectrum of specific wear rates was determined as a function of the sliding distance, considering different microstructure length scales. Finally, experimental equations are proposed to represent a possible range of wear volume and wear coefficient according to the dendrite arm spacings.
Length scale of solidification microstructure tailoring corrosion resistance and microhardness in T6 heat treatment of an Al–Cu–Mg alloy.
(2020) Barros, André dos Santos; Cruz, Clarissa Barros da; Silva, Maria Adrina Paixão de Souza da; Cheung, Noé; Garcia, Amauri; Rocha, Otávio Fernandes Lima da; Moreira, Antônio Luciano Seabra
The combined effects of solidification microstructure refining scale and T6 heat treatment conditions on corrosion behaviour and Vickers microhardness of an Al–3 wt-% Cu–0.5 wt-% Mg alloy were studied. Then, representative samples having quite distinct primary dendritic spacings were solution treated at 495°C for 3 h and artificially aged at 200°C during different times. It was found that the feature of finer solidification microstructure having higher corrosion current density and higher microhardness can be inherited to subsequent T6 heat treatments. In contrast to the as-cast condition, the aging times of 0.5 and 1 h were shown to promote lower corrosion rates without corrosion occurring at the central region of Al-rich matrix. On the other hand, the aging time of 3 h led to a significant decrease in both the corrosion resistance and the microhardness. Finally, a comparative analysis with other works from the literature was also conducted.