Effect of superimposed oscillations on creep behaviour of Al – 2 4·.5Cu and Al – 2 4·5Cu – 2 0·1In (wt-%) alloys containing θ ′ precipitates

The behaviour of both transient and steady state creep of Al – 4·5Cu and Al – 4·5Cu – 0·1In (wt-%) alloys was investigated using a constant stress where torsional oscillations of different frequencies and shear strain amplitudes were operated at various working temperatures. An augment in both transient and steady state creep rates was observed by increasing both frequency and shear strain amplitude of the applied oscillations. The mean values of the activation energy of both alloys for both creep stages were found to be equal to that quoted for dislocation intersection mechanism.