Caracterização de uma liga de Zn-Al-Fe-Cu produzida por processo de fundição convencional em molde metálico

Abstract

Materials requirements encompass a broad combination of properties to meet specific demands. In this sense, this study is based on compositional modifications from commercial alloy Zamac 5, which presents Zn, Al, Mg and Cu as alloying elements, seeking to ally the properties of hardness, mechanical resistance and low susceptibility to corrosion. The original idea of this work was to modify the alloying composition of the Zamac 5 alloy, adding a higher content of Cu and Mg. However, during the processing of the alloy an unexpected phenomenon occurred and modified the objective of this dissertation. This unexpected phenomenon consisted in the observation of the "brazing" of the alloy with the crucible, needing to use excessive mechanical force to extract the alloy from the crucible. Therefore, the alloy produced was Zn-Al-Fe-Cu-Mg with compositional gradient by diffusion of the alloying elements and by the thermal gradient inside of the muffle furnace. The structural characterization of the alloys was performed by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The mechanical characterization was performed through hardness and compression tests. The susceptibility to corrosion was evaluated by potentiodynamic polarization. The results show that a compositional variation, which modifies the microstructure, leads to a modification of the properties of hardness and mechanical strength of the produced alloy. In addition, there was a significant increase in the corrosion resistance of the produced alloy relative to the commercial alloy.