Efeito do teor de zircônio e da deformação no envelhecimento de ligas Al-Zr
Effect of zircon content and deformation on aging of the Al-Zr alloys
Paulo Mendel Fernandes, Carlos Augusto Silva de Oliveira
Resumo
Esse trabalho teve o objetivo de estudar o efeito do teor de zircônio e da deformação na precipitação de ligas Al-Zr (Al-0,2%p.Zr e Al-0,32%p.Zr) durante envelhecimento. As ligas foram obtidas a partir do resfriamento rápido do metal líquido em molde de cobre resfriado com água; posteriormente as amostras foram cortadas, forjadas (50 e 70% de redução de altura) e envelhecidas a 377 ºC por 8, 12, 50, 100 e 400 horas. As microestruturas foram analisadas por microscopia eletrônica de transmissão (MET) e as propriedades foram analisadas por resistividade elétrica e microdureza. As ligas indicaram um pico de endurecimento com 100 horas de envelhecimento devido à precipitação de intermetálicos Al3 Zr cúbicos, após 400 horas as ligas apresentaram redução da microdureza devido ao superenvelhecimento. Tanto a deformação quanto o teor de zircônio influenciaram na precipitação, contudo, foi observado que o aumento da concentração de Zr foi mais significativo para o aumento na precipitação e, consequentemente, aumento do endurecimento das ligas Al-Zr.
Palavras-chave
Abstract
This work aimed to study the effect of zirconium content and deformation on the precipitation of Al-Zr alloys (Al-0.2%wt.Zr and Al-0.32%wt.Zr) during aging. The alloys were obtained from the rapid cooling of the liquid metal in a water-cooled copper mold; after that, the samples were cut, forged (50 and 70% height reduction) and aged at 377 ºC for 8, 12, 50, 100 and 400 hours. The microstructures were analyzed by transmission electron microscopy (MET) and the properties were analyzed by electrical resistivity and microhardness. The alloys indicated a hardening peak with 100 hours of aging due to the precipitation of cubic Al3 Zr intermetallic, after 400 hours the alloys showed reduction of the microhardness due to superaging. Both the deformation and the zirconium content influenced the precipitation, however, it was observed that the increase of the Zr concentration was more significant for the increase the precipitation and, consequently, increase the hardening of the Al-Zr alloys.
Keywords
Referências
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Submetido em:
18/03/2019
Aceito em:
18/05/2021
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