Abstract
The interdendritic fluid flow which is a potential factor controlling casting defects was studied by a simulating experiment on Na- and Sb-modified Al-7% Si alloy castings. The residual liquid in the solidifying alloys was flowed into a tube at different fractions liquid by compressing. The ratio of apparent permeability to viscosity (K/μ) of residual liquid was calculated from the flow rate of the liquid and pressure in D'Arcy's equation. The interdendritic fluid flow is flowable at fractions liquid from 0.8 to 0.3. The ratio K/μ is nearly proportional to the square of the fractions liquid and remains unchanged by Sb-modification at the same fraction liquid. The ratio is, on the other hand, decreased at the same fraction liquid by Na-modification which expands a hydrauric radius. The apparent permeability is almost proportional to the 2.5th power of hydraulic radius which depends on the geometory of dendrites. The ratio K/μ of the Na-modified alloy decreases with an increase in viscosity of the residual lquid.
