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|Type:||Artigo de periódico|
|Title:||Pre-precipitation study in the 7012 Al-Zn-Mg-Cu alloy by electrical resistivity|
|Abstract:||The early stages of pre-aging at near room temperature in an Al-Zn-Mg-Cu based commercial alloy were studied by electrical resistivity. The resistivity changes can be adequately described in the same terms of a Johnson-Mehl-Avrami (JMA) type function for the volume fraction growth of the Guinier-Preston zones or pre-precipitate solute clusters formed. For one specific case, resistivity results were correlated with those obtained using synchrotron-radiation small-angle X-ray scattering (SR-SAXS). Based on the analysis of the parameters of the JMA equation, the existence of a complex diffusion process during pre-precipitation is deduced. An apparent activation energy of 0.69 +/- 0.04 eV for the formation of the above mentioned particles is found. From this energy value, the migration of Mg-vacancy complexes is identified as the main microstructural mechanism responsible for the pre-precipitation. (C) 2002 Elsevier Science B.V. All rights reserved.|
|Editor:||Elsevier Science Sa|
|Appears in Collections:||Artigos e Materiais de Revistas Científicas - Unicamp|
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