Influência da adição de cério na resistência à corrosão e efeito de memória de forma em ligas Fe-Mn-Si-Cr-Ni-(Ce)

Detalhes bibliográficos
Ano de defesa: 2020
Autor(a) principal: Baroni, Luis Felipe Sverzut
Orientador(a): Rovere, Carlos Alberto Della lattes
Banca de defesa: Não Informado pela instituição
Tipo de documento: Tese
Tipo de acesso: Acesso aberto
Idioma: por
Instituição de defesa: Universidade Federal de São Carlos
Câmpus São Carlos
Programa de Pós-Graduação: Programa de Pós-Graduação em Ciência e Engenharia de Materiais - PPGCEM
Departamento: Não Informado pela instituição
País: Não Informado pela instituição
Palavras-chave em Português:
Palavras-chave em Inglês:
Área do conhecimento CNPq:
Link de acesso: https://repositorio.ufscar.br/handle/20.500.14289/13458
Resumo: The interest in scientific and technological development of Fe-Mn-Si-Cr-Ni shape memory alloys is increasing in the last years. The improvement of key properties of theses alloys should enable its use in different applications, such as prestressing concrete structures in civil engineering area. In this context, the present work assesses the cerium (Ce) addition to determine its possible benefits in enhancing both corrosion protection in alkaline media and shape memory effect (SME). The studied experimental alloys were subjected to 0.18%, 0.42% and 0.96% (wt%) of Ce addition, and results were compared to a standard Ce-free alloy. The characterization of such alloys reveals that Ce addition is responsible for a grain size reduction as well as the increase and morphological change in second phase particles. The discussion of the results correlates these microstructural modifications with electrochemical results and SME. Regarding corrosion properties, all samples presented similar passive behaviors in simulated pore solution in absence of chloride ions. When Cl- was added, the sample with 0.18% was the only one to maintain its passivity while other samples showed a major increase in passive corrosion density, indicating a worse stability of the passive film. Pit potential and EIS results showed that the addition of 0.18% of Ce was sufficient to enhance corrosion protection by both changing MnS inclusion morphology and increasing the surface film corrosion protection properties, although it was not high enough to promote oxide, sulfides and intermetallic particles that increases localized corrosion appearance. In terms of shape recovery ratio, an increase in samples with 0.18% and 0.42% of Ce was observed, although there was a reduction in sample with 0.96%. The reduction might be explained by the inhomogeneous microstructure due to the formation of coarse inclusion particles. Finally, the sample with 0.42% presented the best SME results.