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 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.