Effect of Solute Clusters on Low Temperature Aging in Dilute Al-Ag Alloys

Aging of diolute Al-Ag alloys after quenching from low temperatures were studied mainly by electrical resistometry. Maximum resistivity observed in the aging curve of specimens quenched from high temeperature disappeared when the quenching temperature was lowered to 473 or 453K. When the quenching temperature was lowered further to 423K or lower, however, maximum resistivity reappeared. At the temperature lower than or equal to 423K but higher than the GP zone solvus, the alloys were not homogeneous but had clusters of solute atoms or fluctuation of solute concentration. Inhomogeneous distribution of solute atoms may affect the aging behavior after quenching from that temperature.