Zirconium-vacancy binding and its influence on S′-precipitation in an AlCuMg alloy

The binding energy between zirconium atoms and vacancies in aluminium has been measured to be 0.24 ± 0.02 eV. Although the equilibrium solid solubility of zirconium in aluminium is very low the high binding energy results in substantial vacancy trapping in solution treated and quenched alloys. It is demonstrated that this results in modification of precipitation of S′-phase in dilute AlCuMg alloys of solute concentrations similar to that employed in commercial alloy 8090 when lithium is also present.