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|Type:||Artigo de periódico|
|Title:||Al-Fe hypoeutectic alloys directionally solidified under steady-state and unsteady-state conditions|
|Abstract:||The aim of this work is to evaluate the cellular growth, the nature of Al-Fe intermetallic particles and the eutectic arrangement of Al-Fe hypoeutectic samples solidified at growth rates ranging from 0.05 to 2.5 mm/s. The samples grown at higher solidification velocities were obtained using a water-cooled directional solidification apparatus. A Bridgman-type furnace was used to grow samples in the lower range of solidification velocities and an air-cooled mold was used to generate experimental values in between those obtained by the other two techniques of directional solidification. All casting assemblies were set to support upward directional solidification. Based on the present results, a single experimental power law seems to be enough to fit all experimental values of cell spacing as a function of cooling rate. The wide range of solidification thermal parameters used in the present study was chosen due to the diversity of foundry processes used for the manufacture of Al-Fe alloys components. For instance, low solidification velocities are typical of sand casting processes while high velocities are typical of direct-chill (DC) castings. In order to investigate the nature of the Al-Fe intermetallics, these particles were extracted from the aluminum-rich matrix by using a dissolution technique. Such phases were then investigated by SEM-EDAX microscopy and X-ray diffraction (XRD). It was found that Al(3)Fe is the predominant intermetallic phase in the Bridgman-grown samples and Al(6)Fe prevails in the samples grown in the water-cooled solidification apparatus. (C) 2010 Elsevier B.V. All rights reserved.|
|Subject:||Metals and alloys|
|Editor:||Elsevier Science Sa|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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