On the Mechanisms of Aging in Aluminium-Silver Alloys, I

The Specific Heat-Temperature curves of age-hardened samples of Aluminium-Silver alloy have been obtained by the Nagasaki-Takagi method, the results of which are in good agreement with hardness measurements of Köster and Braumann. A discrete step is observed between two clearly defined stages of aging process, the first of which is attributed to creation of the Guinier-Preston Zone (γ'' phase) and the second of which to precipitation of the γ' phase and its transformation to the γ phase. The phase limits of γ'' and γ' (or γ) phases respectively are determined and shown in the phase diagram. The results are discussed and compared with the measurements of X-ray diffuse diffraction effects.