Electrochemical behavior of cast and forged aluminum based in-situ metal matrix composites

Abstract

The present work focuses on the electrochemical behaviour of Al6061 alloy and Al6061-TiB2 in-situ metal matrix composites. Al6061-TiB2 in-situ Composites were synthesized by a stir casting route at a temperature of 860°C using potassium hexafluorotitanate (K2TiF6) and potassium tetrafluoroborate (KBF4) halide salts. Percentage of TiB2 was kept at 0 wt% and 10wt%. The cast Al6061 alloy and Al6061-TiB2 composites (0wt% &10wt %) were subjected to open die hot forging process at a temperature of 500°C. Both cast and forged Al6061 alloy and its composites were subjected to micro-structural and electrochemical characterization. Corrosion behaviour of alloy and composites in both cast and forged conditions were evaluated using electrochemical impedance spectroscopy and the results were backed up by a potentiodynamic polarization test. Results indicate that addition of TiB2 particles increases the corrosion rate and reduces the polarization resistance of aluminium alloy in both cast and forged condition owing to galvanic coupling between the reinforcements and base metal. Further, when compared with cast alloy and its composites, forged alloy and its composites exhibited poor corrosion resistance under identical test conditions.