The photoacoustic technique and the thermal relaxation method were used to determine
the thermal conductivity of some representative samples obtained from an aluminumsilicon
casting alloy A319. This material was solidified with an imposed unidirectional
thermal gradient to obtain samples with different microstructures characterized by the
secondary dendrite arm spacing, which increases as the solidification rate decreases. It
was found that the thermal conductivity of the alloy decreases with an increase in the
secondary dendrite arm spacing and a decrease in the integral dendrite perimeter
