Ag-rich phase formation in the Cu-6 wt% Al alloy with Ag additions

Ag-rich phase formation in the Cu-6 wt% Al alloy with additions of 4, 6, 8, 10, and 12 wt% Ag was studied using microhardness changes with temperature and time, differential thermal analysis (DTA), scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDX), and X-ray diffractometry (XRD). The results indicated that the Ag-rich phase formation follows two different processes depending on Ag concentration. For alloys with 4 and 6 wt% Ag the precipitate formation occurs as a second-order mechanism while for alloys with 8, 10 and 12 wt% Ag a zero-order reaction was observed. (C) 2008 Elsevier Ltd. All rights reserved.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP