Mechanical properties and corrosion behaviour of Al-Si alloys for IC engine

摘要

The paper describes the mechanical properties and the corrosion behaviour of three Al–Si alloys in 0.5 M NaCl solution. The alloys have exhibited similar values of hardness, but the highest tensile strength and the lowest elongation have shown the specimens of alloy with 11.38 % of silicon. Higher content of both copper and magnesium has contributed to better tensile strength and lower elongation of as-cast hypoeutectic alloys. The harmful effects of iron on mechanical properties of all alloys have been reduced to some extent by nickel and cobalt addition. The differences in the values of the open circuit potential of the examined alloys were insignificant. The thickness of the protective oxide layer has increased over time, and the layer has become very compact. Slight differences in the values of the corrosion potential of the alloys were determined, whereas the lowest value of the corrosion current was indicated for the hypereutectic alloy. The presence of intermetallic phases in the alloys has shown that the oxide film was not consistent. The severe pits have not been found at the surface of the corroded samples. Based on the obtained results, the examined alloys may be used for the manufacturing of the internal combustion engine parts.