The Effect of Zr and Y on the Corrosion Behavior of T6-Treated Al–Si–Mg Alloys

TL;DR

This paper studies how adding Zr and Y affects the corrosion resistance of a specific aluminum alloy after heat treatment.

Contribution

The study reveals that Zr improves corrosion resistance while Y increases it, due to changes in microstructure and corrosion mechanisms.

Findings

Adding 0.2 wt% Zr refines α-Al grains and promotes a uniform passive layer, reducing corrosion.

Adding 0.3 wt% Y increases corrosion rate by altering Si particles and enhancing galvanic coupling.

XRD, SEM, and XPS analyses show microstructural and electrochemical changes due to Zr and Y.

Abstract

The microstructure evolution and corrosion behavior of T6-treated Al–Si–Mg alloys were investigated in the presence of Zr and Y additions by using X-ray diffractometry (XRD), optical microscopy (OM), scanning electron microscopy (SEM), electrochemical measurement, and X-ray photoelectron spectroscopy (XPS). The results show that the coarse dendritic α-Al was refined into finer, equiaxed grains by adding 0.2 wt% Zr, which further promoted the formation of a uniform and dense passive layer in 3.5% NaCl solution at room temperature (≈25 °C). In contrast, the Al–Si–Mg alloy containing 0.3 wt% Y exhibited the highest corrosion rate. This phenomenon arises from converting rod-like eutectic Si particles into a spherical morphology, which exacerbates the intergranular corrosion network and enhances galvanic coupling effects.

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