# 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.

## Key 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.