Effect of Fe, Ni and Cr addition on the wear behavior of hyper-eutectic Al-Si automotive alloy has been studied. Dry sliding wear tests have been conducted using pin-on-disc wear testing machine under normal loads of 20N and constant sliding speed of 0.64 ms-1. Influence of Fe addition to the base alloy increases the wear rate due to the formation of needle beta intermetallics. Ni addition to the alloy does not impede formation of needle-like intermetallic compounds and has no positive effect on the modification of microstructure. Introducing of Cr to the iron-rich alloy changes the beta intermetallics into the modified alpha phases and therefore reduced the detrimental effect of iron. As a result it recovers the strength and wear properties of the experimental alloy. Wear test surfaces were examined by SEM and have shown that Cr added alloy improves wear resistance through mild and smooth abrasive grooves filled with oxides.

The main focus of this study is to examine and evaluate the effect of Fe, Ni and Cr on the corrosion behaviour of hypereutectic Al-Si automotive alloy in 3.5% NaCl solution. Experimental information are attained using conventional gravimetric measurements under different solution temperature and velocity and complemented by resistivity, optical micrograph, scanning electron microscopy (SEM) and X-ray analyzer (EDX) investigations. All the alloys show the negative corrosion rate due to formation of a very thin film of aluminum oxide and hydroxid on the surface. Intermetallic particles in the alloys play a major role in passivity. Temperature accelerates the corrosion and the higher velocity breakdown of the passive film. It also affects the resistivity of the alloys. The results from this study also indicate that the temperature and velocity increase the negative corrosion rate of the alloys due to higher rate of chemical reactions. SEM and EDX analysis indicate that the surfaces compose with a thin layer of aluminum oxide and hydroxide corrosion products.

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