Effect of γ/ and γ/ (Ag2Al) Precipitates on the Steady State Creep of Al-16 wt% Ag Alloys with and without Zr Addition

Abstract

The steady state creep behavior of A1-16 wt% Ag and A1-16 wt% Ag-0.1 wt% Zr alloys has been studied at constant load (= 137.2 MPa) and tested at different working temperatures for samples aged at temperatures favouring the formation of y' and y precipitates. It was found that addition of Zr to A1-16 wt% Ag alloy accelerates the precipitations y' and y due to the formation of the meta stable phase A13 Zr. For both alloys, two values of activation energy have been obtained as (34f0.3) kJ/mol for viscous glide of dislocations due to the existence of precipitates and (68 f 0.3) kJ/mol for grain boundary diffusion due to the existence of y precipitates. TEM investigations of y' and y precipitates confirmed the above mentioned effect of Zr addition.