Scientific Research and Practice on the Machinable Hypereuteetic Al-Si Alloys Material

This paper studies systematically the machinability -of Al-18-20%Si hypereutectic alloy. The results indicate: in squeeze casting, adopting high temperature pouring, high cooling Speed, single-modificating with p and T₆ heat treating can make this material free cutting only using common carbide tool. Furthermore, the automobile pistons of this material can be produced in batches.

The single-modlficating with p in squeeze casting may refine the crystals of primary si to 25 urn below and the eutectic si can also be refined and spheroidized. Therefor, pistons of Al-18%si alloy have excellent mechanical and physical properties.

This paper discusses and analyzes the growth morphology and mechanism of si crystals.