Relationship between fluidity and microstructure of aluminum silicon alloy

Abstract

Fluidity of casting alloys is defined as the ability of molten metal to fill mold cavity completely. In this research, fluidity of aluminum alloy grade AC2B, AC4CH, AC4B, AC9A, ADC12, and ADC14 was measured using reducing vacuum technique. Other parameters such as tube materials (copper, stainless steel, and quartz), tube diameters (from 2 mm to 6 mm), applied suction pressure (from 1.33 to 95 kPa), and degree of superheat (from 0 to 120 K) are investigated. Fluidity length of every alloy and condition varies linearly with the square root of suction pressure. Alloys with high silicon content exhibit higher fluidity. Effective suction pressure, defined as applied suction pressure minus gravity and surface energy terms, varies linearly with fluidity. Theoretical analysis indicates that the surface energy can be calculated from the experiments by fitting with curves which pass through the origin. Minimum applied suction pressure required to suck the liquid was calculated and is in the range from 40 to 200 Pa depending on the type of alloys. Microstructure of solidified specimen in the tubes was observed and agrees with the fine channel flow mechanism proposed earlier by Flemings.