External electric field applied during solution heat treatment of the Al-Mg-Si alloy AA6022

The application of an external dc electric field E = 5 kV/cm during the solution heat treatment (SHT) of AA6022 at 475–552°C increased the as-quenched resistivity. An increase continued throughout subsequent natural aging, and there occurred an increase in the tensile properties for the T4 temper. The increase in yield and tensile strength produced by the electric field applied during the SHT is equivalent to a reduction of 10–25°C in the SHT temperature. A thermodynamic analysis of the results indicated that the field reduced both the enthalpy ΔHs and entropy ΔSs of solution, giving a reduction in Gibbs free energy ΔGs, and in turn an increase in solubility of the alloying constituents.