Abstract

VALADEZ, SERGIO; ZANATTA, ADRIANNI; ROBLES, SAID  and  VALDEZ, SOCORRO. MICROSTRUCTURAL ANALYSIS OF Al-Mg-Si-Zn ALLOY. Dyna rev.fac.nac.minas [online]. 2010, vol.77, n.163, pp.9-12. ISSN 0012-7353.

As a part of an overall effort to develop a new Al-alloy appropriated for structural applications, a characterization research was directed towards the development of microstructure and their relationship with heat treatment. The Al-Mg-Si-Zn was chose for that purpose due to the presence of precipitates in a-Al matrix and at grain boundaries, capable to get an excellent relationship between hardness and mechanical resistance. With regards to microstructure, this was characterized in the as-cast and as-aged condition. This treatment was carried out in two stages, the first one at 450ºC during 3 hr which correspond to homogenization treatment and the second one, the ageing treatment at 160 ºC 1hr. Results of microstructure characterization in the as-cast ingots showed the a-Al dendrites, and in addition the presence of a binary eutectic and particles of Mg₇Zn₃ type in interdendritic regions. The eutectic and particles were modified by the aged treatment. Transmission electron microscopic observations carried out in specimens with and without heat treatments showed a uniform distribution of precipitates with different morphologies like cubic, spherical and platelet; in the matrix, which were no detected during the scanning electron microscope observations.

Keywords : Microstructure; eutectic; precipitates; heat treatment.

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