Influence of dendrite arm spacing on the thermal conductivity of an aluminum-silicon casting alloy

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