Effect of Li on Corrosion Resistance of Nearly Eutectic Al-Si Casting Alloys

Abstract

Lithium was added into ZAlSi12 casting alloys to produce Al-Si-Li alloys containing 0%Li, 1%Li, 2%Li and 3%Li respectively. The corrosion performance of the alloys containing various content of lithium was tested by the Tafel polarization curves and the alloys were dipped thoroughly into the solution of 5% NaCl. The surface appearance of the alloys after corrosion was observed by Scanning Electron Microscopy, the composition of corrosion products was determined by Energy Dispersive Spectrometer. The results show that the corrosion resistance of ZAlSi12 casting alloys is improved by the addition of lithium. The alloy has an optimum corrosion resistance when the lithium content is 2%, and then the corrosion resistance decreases as increment of lithium content.