Abstract
The early stage of aging in Al-1-15at%Ag alloys was investigated by means of electrical resistivity and specific heat measurements and X-ray diffraction method. The η'-zones are formed immediately after quenching and spherical G.P. zones are subsequently formed in the early stage of aging. The spherical G.P. zones formed at lower temperatures consist of an ordered arrangement of Ag atoms (ordered state, η-zone). Those formed at elevated temperatures, on the other hand, consist of a disordered arrangement of Ag atoms (disordered state, ε-zone). The η- and ε-zones reversibly transform from one state to another at the transition temperature. The experimental transition temperatures are 140° to 160°C for Al-1-3at%Ag alloys and 160° to 180°C for Al-5-15at%Ag alloys.
