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Master's Dissertation
DOI
Document
Author
Full name
Felipe Gianiselle
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2019
Supervisor
Committee
Padilha, Angelo Fernando (President)
Kliauga, Andrea Madeira
Lima, Nelson Batista de
Title in Portuguese
Evolução microestrutural durante o processamento da liga de alumínio AA 7108.
Keywords in Portuguese
Alumínio
Extrusão
Ligas leves
Solidificação
Tratamento térmico
Abstract in Portuguese
Componentes extrudados da liga de alumínio AA 7108 pertencente ao sistema Al-Zn-Mg são frequentemente utilizados na área de transporte. No presente trabalho, a microestrutura da liga 7108 foi estudada nas seguintes condições: bruta de solidificação, após homogeneização e após extrusão. Foram utilizadas as seguintes técnicas complementares de caracterização microestrutural: microscopia óptica, microscopia eletrônica de varredura (MEV), microanálise por dispersão de energia acoplada ao MEV, difração de raios X, medidas de dureza Vickers e de condutividade elétrica. Após solidificação, a liga apresentou estrutura dendrítica, microssegregação e compostos intermetálicos. Após tratamento de homogeneização por cerca de 10 horas a 486ºC, ocorreu dissolução quase completa das partículas de intermetálicos e diminuição da microssegregação. Foi detectada também a presença da fase Al3(Zr,Ti), que não se dissolveu durante tratamento térmico de homogeneização de até 20 horas de duração. Durante a extrusão ocorreu recristalização com significativo refino de grão, além de formação de zona periférica de grãos grosseiros. A técnica de difração de raios X utilizando o método proposto por Williamsonn e Hall mostrou eficaz e promissora para acompanhar a homogeneização.
Title in English
Microstructural evolution during homogenization of aluminum alloy AA 7108.
Keywords in English
Aluminum alloy AA 7108
Extrusion
Heat treatments
Microstructrure
Processing
Solidification
Abstract in English
Extruded components of the aluminum alloy AA 7108 belonging to the Al-Zn-Mg system are often used in the transport area. In the present work, the microstructure of alloy 7108 was studied in the following conditions: after solidification, after homogenization heat treatment and after extrusion. The following complementary techniques of microstructural characterization were used: optical microscopy, scanning electron microscopy (SEM), energy dispersive microanalysis coupled to SEM, X-ray diffraction, Vickers hardness measurements and electrical conductivity. After solidification, the alloy presented dendritic structure, microssegregation and intermetallic compounds. After homogenization heat treatment for about 10 hours at 486 °C, almost complete dissolution of the intermetallic particles occurred and decreased microssegregation. The presence of Al3(Zr, Ti) phase was also detected, which did not dissolve during the homogenization heat treatment of up to 20 hours. During extrusion, recrystallization occurred with significant grain refining, in addition to formation of peripheral coarse grains zone. The technique of X-ray diffraction using the method proposed by Williamsonn and Hall showed effective and promising to accompany the homogenization.
 
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Publishing Date
2019-05-09
 
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