ISSN:
1662-9779
Quelle:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Thema:
Physik
Notizen:
The rheological behavior of semisolid aluminium alloy (A356) slurry is investigated byusing a concentric cylinder viscometer under high cooling rate (30 to 50°C/min) and high shear rate(650 to 1500s-1) conditions. Two different series of experiments are carried out. In all of theseexperiments, the pellets of A356 alloy are poured into the outer cylinder where they melt completelyby resistance heating. When the inner cylinder is placed concentrically, the molten metal resides inthe annular space between the cylinders. As the inner cylinder rotates, the alloy is shearedcontinuously during cooling from a temperature of 630°C, and a slurry forms. In the first series ofexperiments, for different cooling rates, shearing continues under a constant shear rate until rotationof the inner cylinder stops. During experiments, the temperature of the slurry is measuredcontinuously using a K-type thermocouple, from which the solid fraction is calculated. In the secondseries of experiments, the molten alloy is cooled and sheared continuously at different shear ratesfor a given cooling rate. The apparent viscosity of the slurry is calculated by measuring the torqueapplied to the inner cylinder and its rotational speed. The results show that the slurry viscosityincreases with increasing fraction of solid and increasing cooling rate, and it decreases withincreasing shear rate. At high values of shear and cooling rates, the viscosity varies gradually up to asolid fraction of about 0.5
Materialart:
Digitale Medien
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/02/24/transtech_doi~10.4028%252Fwww.scientific.net%252FSSP.141-143.409.pdf
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