I had tried many time to cast Al-7Si alloys through the rapid slurry formation (RSF) process at different rpm e.g. 400, 600, 800, 1000, 1200, 1400 rpm. At low shear rate 400-800, the temperature was in the control but at shear rate 1000 or above then the temperature started to decrease below the eutectic temp (577 degree C) and temp was about 570 degree C. As we know that in this RSF process, the temperature after stirring should be above 577 degree C but I am not able to control the temperature.
Dear Robin Gupta,
I make some preliminary remarks.
1. 'Why"-questions rather belong to the domains of religion and philosophy than to those of science.
2. The following remarks are made assuming that all your processed Al-7wt%Si alloys have the same composition, both in terms of the primary alloying element as for the amount of secondary elements like grain refiners present.
3. Increasing rpm beyond a certain level may be equivalent to increase the supercooling; this might account for the observed temperature decrease, thereby shifting the eutectic point
4. Increasing rpm might also affect the grain size of the primary solidifying primary Al phase as well as the particle size of the precipitating secondary (Si) phase.
5 Would it be possible to study the amount of eutectic solidification as a function of rpm?
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