The multi-phase alloys are the most popular engineering materials, where one phase acts as the matrix and the others serve as the reinforcing elements. This kind of microstructure can be obtained directly through the solidification method. Therefore, it is of vital importance to guide the solidification process in the way favorable to controlling the species, volume fraction, morphologies and sizes of the reinforcement phases. In our recent researches, the solidification of Al-Si-Mg alloy is studied with the stresses on the effect of cooling rate on the reinforcing phases, Si and Mg{sub}2Si. The formation order of Si and Mg{sub}2Si is mainly dependent on the concentrations of Si and Mg, but also influence by the cooling rate. By changing the cooling rate, the formation order as well as the volume fractions of Si and Mg{sub}2Si phases during the solidification can be changed due to the solute redistribution. The detail regulation was confirmed by both experimental results and numerical modeling results.
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