Ws. Kim et al., MODEL OF THE EFFECT OF ALLOY CONTENT ON SHELL STRENGTH DURING SOLIDIFICATION OF BINARY-ALLOYS, Journal of thermal stresses, 18(6), 1995, pp. 579-602
A thermomechanical model of unidirectional solidification of binary al
loy systems is presented. The goal of the model is to begin to explore
the effect of alloy content on the mechanical behavior of the solidif
ying shell by first examining the effect on lateral strength. The shel
l solidifies onto a semi-infinite mold proceeding behind a mushy zone
that grows into an initially quiescent fluid Deformation of the shell
is modeled with a thermolypoelastouiscous constitutive law that allows
for examination of the idealized case of elastic deformation of the c
asting as well as the case where strain rate relaxation due to viscous
creep predominates. Any effects of alloy content on the coefficients
in the constitutive model are ignored so that the calculated effects o
n strength arise entirely from the size of the mushy zone. Aluminum-ma
gnesium alloys solidifying onto a copper mold are considered as specif
ic examples using a linearized portion of the Al-Mg phase diagram. The
material with the smallest alloy content exhibits the greatest shell
strength for the same cooling histories. That material with the widest
freezing range has the lowest strength. For the elastic model, the av
erage strength always increases with time, whereas for the elastovisco
us case it can decrease with time to the point where the alloy content
has virtually no effect on strength.