Improved corrosion behavior of ultrafine-grained eutectic Al-12Si alloy produced by selective laser melting

Although the parts produced by selective laser melting (SLM) are reported to possess comparable or better mechanical properties than the traditionally processed counterparts, the SLM-produced parts demonstrate slightly unfavorable corrosion resistance properties compared with their traditional counterparts. This work shows that, in addition to rapid manufacturing of parts, SLM can effectively refine the grains of eutectic Al-12Si alloy. The SLM-produced Al-12Si shows an ultrafine-grained microstructure and improved corrosion resistance, which provides an innovative and efficient approach to refine the silicon particles in eutectic Al-12Si alloy. Unlike the microstructured Al-12Si alloy manufactured by traditional casting, the SLM-produced Al-12Si alloy contains ultrafine-grained eutectic silicon particles distributing in the aluminum substrate. Importantly, it is found that the SLM-produced Al-12Si alloy possesses superior corrosion resistance than the cast Al-12Si alloy in terms of the results from electrochemical methods and weight loss test. The favorable corrosion resistance of SLM-produced Al-12Si is attributed to these ultrafine silicon particles, which prominently benefits for the formation of the oxide film. The influence of the microstructure with regard to eutectic silicon particles size on the corrosion resistance has also been discussed in depth.