The second phases of Mg–xAl–ySi–Ca alloys and their influences on properties

Abstract

The types and changes of the second phases in the Mg–xAl–ySi–0.3Ca alloys and their effects on the properties of the alloys were studied. The results showed that within a certain range of Si and Al content, Si had the greatest influence on the size of the Mg₂Si phase, while Al content affected the size and morphology of Mg₁₇Al₁₂ and Mg₂Si phases. The CaMgSi phases were less affected by the Al and Si content. In a tensile test, the as-cast alloy had the best performance when it contained small Mg₁₇Al₁₂ and Mg₂Si phases, and the Mg₁₇Al₁₂ phase was more likely to become the fracture source. The alloy we tested with the best corrosion resistance was Mg–4Al–0.7Si–0.3Ca alloy, the worst was Mg–6Al–0.7Si–0.3Ca alloy.