MICROSTRUCTURE AND THERMAL PARAMETERS DURING DIRECTIONAL SOLIDIFICATION OF A TERNARY AL-FE-MG ALLOY
Mateus Rovigati Gandolfi1; Leonardo Fernandes Gomes1; Bismarck Luiz Silva1; José Eduardo Spinelli1
1 Department of Materials Engineering, Federal University of São Carlos, UFSCar, São Carlos, SP,Brazil
doi:10.20906/CPS/COB-2015-2711
Resumo
Al-Fe alloys containing from 2.0 to 4.0wt%Mg characterizes chemical composition of some comercial alloys 5xxx series such as 5454, 5086 or 5083. These alloys are indicated for petrochemical platforms structures and shipbuilding industry due to their resistance to seawater and high humidity. The effects of magnesium addition in Al-Fe alloys are not properly established, mainly, considering the examination of aluminium α phase growth mode, the prevalence of eutetic phases and segregation. In contrast, Al-Fe alloys solidification is widely known from the point of view of microstructural analysis and thermal solidification parameters, namely growth rate (VL) and cooling rate (ṪL). The Iron addition near the eutetic composition allows to obtain higher mechanical strength, which is associated with the higher density and amount of hardening phases forming within the eutetic mixture. The present study aims to evaluate the addition of 1.2wt%Mg on the Al-1.5wt%Fe base alloy in order to obtain some resulting characteristics, such as the influences of thermal solidification parameters (growth rate - VL and cooling rate - ṪL) on the microstructure of the aluminium alloy solidified under unsteady-state conditions. Samples were obtained by upward directional solidification (DS), followed by characterization through metallography, scanning electron microscopy (SEM) and X-Ray diffraction. The experimental microstructural evolution was determined for the ternary alloy so that it could be compared with that typically established for the directionally solidified Al-Fe alloy.
Palavras-chave: Metals and alloys; Microstructure; Solidification; Al-Fe alloys; Casting