Towards an integration of flow behaviour and microstructural evolution during superplastic deformation of microduplex alloys

Superplastic behaviour and concurrent microstructural evolution in microduplex alloys are reviewed to bring out the following less common trends reported in the literature. An anomaly exists about the shape of the log (stress)-log (strain rate) curves and the parameters of the constitutive relationship. Also, some microduplex alloys exhibit two values of activation energy for superplastic deformation with a lower value at T less than or similar to 0.8T(m). The ratio of the two activation energies is approximately equal to 0.55. The co-existing two phases and the alpha/alpha, alpha/beta and beta/beta boundaries contribute differently to deformation and cavitation, but grain coarsening occurs in a concerted manner.