Abstract
Superplasticity over the wide ranges of both temperature and strain rate has been investigated for a 5083 aluminum-magnesium base alloy. Large elongations of more than 300% were obtained in a temperature range of over 200 K and in a strain-rate range of the two orders of magnitude. Such large elongations were attributed to both grain boundary sliding and solute-drag controlled creep mechanisms. Fractography has been performed systematically in the light of deformation mechanism and elongation to failure. In a low strain rate, granular feature was observed on fracture surfaces. The granular feature was coarsened with increasing temperature. As temperature approached to an apparent solidus, fracture surface was accompanied with typical filaments suggesting the presence of a liquid phase. Near the apparent solidus temperature, a small amount of filaments was found at a strain rate of 1.4 × 10−2 s−1, while distinct intergranular fracture was found at 2.8 × 10−1 s−1. Consequently, it is reconfirmed that the morphology of fracture surface is correspondent with deformation mechanisms and elongation to failure.
