Influence of the thermal parameters on the microstructure, corrosion resistance and hardness on the unidirectional solidification of Al-10wt% Si-5wt% Cu alloy

Abstract

This study aims to correlate thermal parameters in the directional solidification of Al- 10wt% Si-5wt% Cu alloy with the resulting microstructure and, in addition, with hardness and corrosion resistance. The results include primary dendritic arm spacing (PDAS), tip growth rate (VL), cooling rate (TR), scanning electron micrographs (SEM), hardness values and corrosion resistance parameters obtained by electrochemical impedance spectroscopy (EIS) and by the Tafel extrapolation method, conducted in 3% (m/v) NaCl solution at room temperature. The results show that coarser PDAS exhibit a tendency to increase in corrosion resistance, except in the positions with higher concentrations of the intermetallic compound Al2Cu, that surrounded by an aluminum rich phase tends to have a higher resistance to corrosion. The hardness values remained constant.