Effects of quenching temperature on G. P. zone formation in Al-Cu and Al-Zn alloys

Abstract

Behaviors of G. P. zone formation and growth in Al-Cu and Al-Zn alloys were investigated by means of electric resistivity measurements and X-ray small angle scattering method. Resistivities of both alloys unchange in a certain period of aging time in which the X-ray integrated intensity is saturated (flat region). The limit-temperature for G. P. zone formation determined by the resistivity at the flat region is peculiar to the concentration of the alloys and independent of the quenching temperature. These results imply the existence of a metastable miscibility gap in both alloys. The resistivity at the flat region is considerably influenced by the quenching temperature, because the G. P. zone's distribution (zone size and its density) at the flat region changes with the quenching temperature although the volume fraction of zones is the same.