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High silicon aluminum alloy has the advantages of low density, high strength, wear resistance, good dimensional stability, However, due to the existence of a coarse primary silicon in high-silicon aluminum seriously fragmented matrix, and the deterioration of the performance of materials, restrictions its industrial applications. Mainly through the modification, semi-solid-state technology, Suspension Casting to improve primary silicon morphology, but these means there are ineffective or complex technical conditions, high cost, and is not suitable for large-scale industrial production. Multi-plate sheet for high silicon aluminum primary silicon organization exists, and the uneven distribution of this article aims of the two components of high silicon aluminum alloy Al-25% Si and Al-30% Si alloy extrusion deformation grain refinement, so that a more uniform distribution of the primary silicon, and is heated by diffusion, secondary heating and other means in order to obtain a fine round the primary silicon particles, and contrast specific refinement effect. The study showed that: compressional deformation can significantly improve the morphology of primary silicon, squeeze the large primary silicon cratering before alloy, plate-like primary silicon lap star petals primary silicon extrusion breaks collide with each other, at the same time in the extrusion the primary silicon occurs grew up phenomenon, containing more coarse primary silicon refinement of the Al-30% Si alloy is better than Al-25% Si alloy; through diffusion heat treatment and found that with the proliferation of the improvement of the heating temperature, holding time, the primary silicon will gradually grow, and primary silicon passivation phenomenon occurred, but the holding time is too long when the primary silicon lap phenomenon, but deterioration of the newborn silicon morphology; in the secondary heating process, the alloy has undergone a eutectic silicon fuse in the amount of liquid phase is formed in the alpha phase clearance unmelted, liquid volume expanded surrounded by α-phase, α-phase is completely melted to form a liquid phase with primary stages of silicon particles coexist organization, reheating in primary silicon occurs significantly spheroidization; secondary heating heating effect to improve the effect of primary silicon than diffusion, but diffusion heating then reheated primary silicon ball phenomenon is more pronounced diffusion heat treatment after reheating the best option. This paper compressional deformation, diffusion heating, reheating means of primary silicon particles refinement spheroidization, and achieved good results, has good practical value. The test equipment requirements low, simple and feasible, with better results, explore a new idea of ??the improvement of primary silicon morphology.
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