Effect of Structural Modification on Corrosion Behavior of Hypo Eutectic Al-Si Alloy

Muhammad Mansoor,Shaheed Khan,Muhammad Kamran Yaseen

doi:10.4028/www.scientific.net/kem.778.16

Muhammad Mansoor, Shaheed Khan + Show 1 more

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https://doi.org/10.4028/www.scientific.net/kem.778.16

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Abstract

Al-Si eutectic cast alloys are widely used in aeronautical and automobile industries where significantly high strength, toughness and wear resistance are required. This class of cast alloys exhibit relatively low corrosion resistance in brine environments. The mechanical properties of the alloy system mainly depend upon the shape of Si rich eutectic phase, which mainly has acicular geometry. In present research, the effect of modified microstructure of 12 wt. % Si-Al alloy on corrosion behavior was studied. The needle like Si rich eutectic phase was modified to disperse spherical structure using rare earth metal halides. The corrosion rate and pitting behavior of modified and unmodified alloy were evaluated in 3.5% NaCl solution by general corrosion for calculated time. It was observed that the corrosion rate and pitting tendency of modified alloy had been appreciably reduced as compare to unmodified alloy. The improvement of corrosion properties were the attributes of changed morphology and distribution of Si rich eutectic phase.

Highlights

The Al-Si alloy is a binary eutectic alloy having about 11-13% silicon
Modification is the process of adding trace amounts of certain elements to an alloy to change the morphology of the phase(s) present in the alloy [2]
Microstructural features of the alloys were characterized using scanning electron microscope (SEM) in secondary electron mode, which confirmed the modification of the secondary silicon rich eutectic phase (Fig. 1)

Summary

Introduction

The Al-Si alloy is a binary eutectic alloy having about 11-13% silicon. It is frequently used in aeronautical and automobile industries for cylinders, pistons, guiderails, etc. Microstructural features of the alloys were characterized using scanning electron microscope (SEM) in secondary electron mode, which confirmed the modification of the secondary silicon rich eutectic phase (Fig. 1). The corrosion behavior of the specimens under investigations could be influenced by their surface energies.

Results

Conclusion