Cavitation casued by superplastic straining of a fine-grained Al-Mg-Mn-Cu alloy under uniaxial tension has been systematically evaluated. Tensile tests were conducted in the strain-rate range of 10~(-4)s~(-1) to 10~(-2)s~(-1) and in the temperature range of 450 deg C to 550 deg C. Measurements of the number and size of cavities were made by image anlysis through optical microscopy on tested specimens. With increasing imposed strain, the cavity population density increases. Cavity grwoth has been found to be primarily due to the plastic deformation of the matrix. These results are characterized by the total volume fraction of cavities which is found to increase exponentially with strain. However, the dependencies of cavity volume fraction on strain-rate and temperature are not straightforward and the notion of just a few large cavities contrlling the total cavity wolume is not always true. Attempts to explain tehse complex dependencies have been carried out based on the concepts of debonding between the matrix and non-deformable particles, the continuous nucleation of new cavities, and plasticity-based avity growth for large cavities.
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