科研之友
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摘要
The Al-Si alloy ingots used for the study were produced by diluting an Al-Si master alloy containing impurity Fe with pure Al. A type of micron-sized AlFeSi spherical microstructure was observed in the diluted alloy ingot. These spherical particles have an overall diameter range of 2.8-6.1 mu m, with polyhedral Al9Fe2Si2 particles inside and clusters of fine Si particles with sizes concentrated at 200-250 nm outside. During solidification, the AlFeSi atomic clusters in the alloy melt firstly form the polyhedral Al9Fe2Si2 and then a shell of fine Si particles. The internal polyhedral Al9Fe2Si2 particles and the external fine Si particles have different formation mechanisms, with the polyhedral Al9Fe2Si2 particles being dominated by faceted growth and the fine Si particles being dominated by finite growth after nucleation.
