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The transient creep of Al‐16 wt% Ag and Al‐16 wt% Ag‐0.1 wt% Zr solid solution alloys is investigated in the temperature range 428 to 673 K for various ageing times under constant load. The subsequent decrease and increase in the values of creep parameters n and β with increasing ageing times and ageing temperatures has been explained on the basis of structure transformations occuring in Al‐Ag alloys. It was found that the addition of Zr to Al‐16 wt% Ag alloy accelerates the precipitation of GP zones, γ′‐phase, and γ‐phase. TEM investigations confirmed the above effects. The mean values of the activation energy of both alloys were found to be equal to that quoted for dislocation intersection.

-0.1 wt% Zr-0.1 wt% Ti alloys were used to trace the effect of Zr and Ti additions on the behaviour of the steady state creep. After solid solution treatment specimens of both alloys were aged at 623, 673, 723 and 773 K and creep tests were performed at room temperature by applying stresses of 60.0, 62.4, 64.7 and 67.1 MPa. The results showed a sound stabilization effect of Zr and Ti on the ageing characterstics of binary Al-1 wt% Si alloy. Values of the applied stress sensitivity parameter, m, obtained were in the range of (20-34) for Al-Si alloy and (14-19) for Al-Si-Zr-Ti alloy. Time to rupture was found to be strongly increased by Zr and Ti additions. The activation energies of the precipitation process involved were found to be 81.9 kJ/mole and 33.7 kJ/mole of the Al-Si and Al-Si-Zr-Ti alloys respectively.

The steady state creep behaviour 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 metastable phase A13Zr. 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 abovementioned effect of Zr addition.

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