THE EFFECT OF STRONTIUM ON THE ELECTRICAL-RESISTIVITY AND CONDUCTIVITY OF ALUMINUM-SILICON ALLOYS

Electrical conductivity and resistivity measurements have been conducted on Al-Si and Al-Si-Sr alloys containing up to 12.6 wt pct silicon and 0.035 wt pct strontium. While silicon decreases the electrical resistivity of aluminum, strontium has no effect as it neither dissolves appreciably in aluminum nor changes the silicon solubility. Strontium does, however, retard the rate of silicon precipitation from supersaturated solid solution. When eutectic silicon appears in the microstructure strontium increases the conductivity of the alloy by up to 10 pct at the eutectic composition. Determination of the resistivity of directionally frozen eutectic samples demonstrates that this difference is due to changes in the silicon morphology. © 1991 The Minerals, Metals and Materials Society, and ASM International.