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Type: Artigo de periódico
Title: Influence In The Microstructure And In The Microhardness Regarding The Effects Of Adding 4%ag In The Al-4%cu Unidirectionally Solidified Alloy
Author: Faria
Jonas Dias; de Brito
Crystopher Cardoso; Paixao de Sousa Costa
Thiago Antonio; Verissimo
Nathalia Carolina; Reis Santos
Washington Luis; da Silva Dias Filho
Jose Marcelino; Garcia
Amauri; Cheung
Abstract: Al-Cu alloys are used in several industrial applications, such as automotive and aerospace manufacturing, which demand mechanical strength and toughness performances. The Al-Cu-Ag ternary alloy system has been investigated to obtain a better understanding on ternary eutectic alloys besides its inherent applications. However, studies concerning the effects on microstructure and hardness due to Ag addition on Al-Cu alloys solidified under transient conditions, are not found in literature. In this sense, the main objective of this work consists in investigating the solidification parameters such as growth (V-L) and cooling (T)over dot rate, microstructure and microhardness regarding the effects of adding 4wt% Ag on a Al-4wt% Cu alloy unidirectionally solidified vertically upwards under unsteady-state solidification conditions. Experimental growth laws correlating the primary (lambda(1)) and secondary (lambda(2)) dendritic spacings with growth and cooling rate are proposed for Al-4wt%Cu and Al-4wt%Cu-4wt% Ag alloys. X-Ray Diffraction (XRD) analyses were performed in order to determine the crystalline phases of the compounds present in the alloys microstructure. The diffractogram of the binary alloy showed the presence of theta-Al2Cu, Al-Cu, Al4Cu9 and Al6Fe intermetallics and, for the case of the ternary alloy, the mu-Ag3Al intermetallic was detected. Chemical compositions at the boundary regions of the dendrite as also inside the dendrite were obtained using scanning electron microscope (SEM) connected to an Energy-Dispersive Spectrometer (EDS) system. Several positions along the ingot were analyzed through the X-Ray Fluorescence (XRF) technique permitting the detection of macrosegregation occurrence. It is shown that the microhardness is not influenced by both spacing patterns of the Al-rich matrix. The rho-Ag2Al and mu-Ag3Al intermetallics are responsible for the increase in hardness due to the interaction with ternary dendrite arm spacing and other intermetallics.
Subject: Al-cu Alloys
Citation: Influence In The Microstructure And In The Microhardness Regarding The Effects Of Adding 4%ag In The Al-4%cu Unidirectionally Solidified Alloy. Univ Fed Rio De Janeiro, Lab Hidrogenio, v. 20, p. 992-1007 OCT-DEC-2015.
Rights: fechado
Identifier DOI: 10.1590/S1517-707620150004.0103
Date Issue: 2015
Appears in Collections:Unicamp - Artigos e Outros Documentos

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