Study on the extruded structure of rapidly solidified hypereutectic Al-Si alloys

摘要

Hypereutectic aluminum silicon alloys are used extensively as piston materials due to their low coefficient of thermal expansion and high wear-resistance. Since casting technology cannot solve the problem of primary silicon coarsening, rapid solidification (RS) technology has been used to fabricate hypereutectic Al-Si alloys. Compared with casting alloys, properties of RS hypereutectic Al-Sic alloys are greatly improved because of the refining of the silicon phase and solubility extension of alloy elements [1-3]. These kinds of materials draw more and more attention world-wide and some automobile factories in Germany and Japan have put them into commercial applications [4, 5]. However, the high cost of the complicated fabrication process limits its industrial use. In order to solve this problem, it is important to understand the densification mechanism of RS hypereutectic Al-Si alloys.