INFLUENCE OF TRACES ADDITION OF TIN ON THE GROWTH AND ON THE COARSENING OF THE GUINIER-PRESTON ZONES IN Al-10% at.Ag ALLOY

Abstract

The formation of the Guinier-Preston zones in aluminium alloys is closely linked with the excess vacancies. Traces of tin added to an Al-Ag alloy exert an influence on the Guinier-Preston zones precipitation. Due to their high binding energy with vacancies, tin atoms trap some of these available to promote the diffusion of silver atoms for the formation of the Guinier-Preston zones. At 125°C, tin microalloying slows down the reaction of the Guinier-Preston zones precipitation. The diffusion coefficient of the solute atoms in the Sn free alloy and in the Sn added alloy are determined during the coarsening regime which obeys to the Lifshitz, Slyosov and Wagner theory.

Keywords

• Guinier-Preston zones
• precipitation
• coarsening
• diffusion
• vacancies
• hardening