Tecnologia em Metalurgia, Materiais e Mineração
https://tecnologiammm.com.br/article/doi/10.4322/tmm.00602006
Tecnologia em Metalurgia, Materiais e Mineração
Artigo Original

ESTUDO DO COMPORTAMENTO MECÂNICO EM TEMPERATURAS ELEVADAS DE LIGAS FeCr COM ADIÇÕES DE Al E Y

HIGH TEMPERATURE MECHANICAL BEHAVIOR OF FeCr ALLOYS CONTAINING Y AND/OR Al

Pillis, Marina Fuser; Ramanathan, Lalgudi Venkataraman; Couto, Antonio Augusto; Andrade, Arnaldo Homobono P. de; Castagnet, Danieli Aparecida P.

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Resumo

Além de elevadas condutividades térmica e elétrica, e alta resistência à corrosão, o material utilizado como interconectores em células a combustível de óxido sólido (SOFC) deve ter propriedades mecânicas adequadas, tanto à temperatura ambiente, quanto em altas temperaturas. O objetivo deste estudo é avaliar o comportamento mecânico à temperatura ambiente e em temperaturas elevadas de ligas FeCr sem e com adição de ítrio e/ou alumínio. As ligas FeCr, FeCrY, FeCrAl e FeCrAlY foram obtidas por meio de fusão a vácuo em forno elétrico à indução. Os lingotes foram forjados e laminados. Foram preparados corpos-de-prova para ensaios de tração realizados nas temperaturas ambiente, 800°C e 900°C. A microestrutura e as superfícies de fratura foram observadas em microscópio eletrônico de varredura. Todas as ligas apresentaram um alto nível de inclusões. A liga FeCrAlY apresentou o melhor desempenho em relação ao comportamento mecânico, em todas as temperaturas investigadas. Todas as ligas apresentaram fratura dúctil, com mecanismo predominante de fratura por microcavidades.

Palavras-chave

Ligas FeCr, Comportamento mecânico, Célula a combustível, Interconectores

Abstract

Materials used as solid oxide fuel cell (SOFC) interconnects should have high electrical and thermal conductivities, high corrosion resistance and adequate mechanical strength at room as well as at high temperatures. In the light of this, the aim of this study is to determine the mechanical behavior of FeCr alloys without and with Y and/or Al additions at room and at high temperatures. Ingots of four alloys, FeCr, FeCrY, FeCrAl and FeCrAlY were prepared by induction vacuum melting and casting. These ingots were forged and rolled. Tensile test specimens were machined from the rolled sheets. The tensile tests were carried out at room temperature, 800°C and 900°C. Scanning electron microscopy was used to examine the microstructure of the alloys and the fractured surfaces after the tensile tests. The microstructure of all the alloys revealed a large number of inclusions. Among the alloys, FeCrAlY has the best mechanical behavior. The fracture surfaces of all the alloys tensile tested at the different temperatures revealed coalescence of micro-cavities (dimples) indicating ductile fracture.

Keywords

FeCr alloy, Mechanical behavior, Fuel cell, Interconnects

Referências

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