A QUANTITATIVE MEASURE OF INTERNAL CAVITATION IN SUPERPLASTIC ALLOYS USING PHOTOACOUSTIC ANALYSIS

Internal cavities often develop during the deformation of superplastic alloys. Experiments were conducted to determine whether a nondestruct ive photoacoustic method may be used to detect the presence of interna l cavities in two different commercial Al-based alloys. An analytical procedure was developed to provide quantitative information on the vol ume fraction of cavitation. The results confirm that the photoacoustic signal can be used to detect the presence of cavities, and it is demo nstrated that the quantitative measurements derived from the photoacou stic data are consistent with observations obtained by sectioning and standard metallographic techniques.