Cast Al-Si-Cu Alloys: Effect of Modification on Thermal and Electrical Conductivities

The effect that modification of cast Al-Si alloys exerts on the thermal and electrical conductivities is presented. The work was conducted by casting a series of samples in a rig that promotes unidirectional solidification to vary the level of microstructure refining, which was assessed by the secondary dendrite arm spacing. The alloys were prepared in a furnace and poured into the rig after adding different amounts of strontium to modify the aspect of the aluminum-silicon eutectic. Measurements were conducted on as-cast and heat-treated specimens. The electrical conductivity tests were referred to the International Annealed Copper Standard. Thermal conductivity of the different samples was obtained by comparing it with that of a high-purity aluminum sample. It was found that either value of conductivity depends on the degree of modification and by heat treating, whereas other microstructural parameters exert a secondary effect.