Effect of Mg on Microstructure and Mechanical Properties of Hypereutectic Al-25Si Alloy

Abstract

Abstract The effects of Mg Addition mode and amount on the microstructure and mechanical properties of hypereutectic Al-25Si alloy after modification were analyzed. The results show that the Mg2Si phase is relatively small, which is in the shape of granular or small bone, and has relatively little damage to the tissue; The hardness of the alloy is directly proportional to the amount of Mg added. When 1.5wt. % Mg is added, the microstructure and properties reach the best state. If the amount of Mg 2Si is excessive, it will gradually change into a coarse mesh, Chinese character shape and deteriorate the properties. The main reason is that there is a close adhesion growth relationship between Mg2Si and eutectic silicon. The modification and refinement lead to the lack of nucleation basement and the inhibition of growth of Mg2Si. At the same time, the modified residual AlP phase is used as the nucleation point. Mg2Si phase did not coarsen obviously, and other phases also maintained in a good shape.