HYPEREUTECTIC AL-SI BASE ALLOY DIE CASTING MEMBER AND PRODUCTION THEREOF

摘要

PROBLEM TO BE SOLVED: To obtain a hypereutectic Al-Si base alloy excellent in the wear resistance, in which the crystallization and the growth of primary phase Si is promoted in a die casting sleeve. SOLUTION: Molten aluminum alloy containing 14-17 wt.% Si is poured into the die casting sleeve and successively, the molten aluminum alloy is held in the temp. range between the primary phase Si crystallizing temp. and the eutectic temp. for 2-5 sec., and after crystallizing and growing the Si primary crystal, the molten aluminum alloy is injected and formed to adjust the average grain diameter of the primary phase Si crystallized in the cast structure into the range of 7-15μm. Filling ratio of the molten aluminum alloy into the die casting sleeve is desirable to hold into the range of 20-40 vol.%. The aluminum alloy to be used can contain further 0.001-0.02 wt.% P.