Characterization by X-ray computed tomography of decohesion, porosity growth and coalescence in model metal matrix composites

Damage mechanisms of model materials have been studied using in situ tensil e tests coupled with high resolution X-ray tomography. This non destructive technique revealed that 50% of the particles were pre-damaged by the extru sion. The initiation and growth phases of the damage process were quantifie d using the three dimensional images. The growth phase, measured both local ly ton isolated particles) and globally tin the entire block) was compared with the Rice and Tracey prediction which was shown to overestimate the glo bal prediction and to give a reasonable agreement of the local growth rate. Discrepancies between prediction and experiments could be partly quantifie d by introducing the effect of the growth threshold in the Rice and Tracey analysis. The scatter in the measured thresholds and growth rates were attr ibuted to local crystallography and to local spatial arrangement effects. ( C) 2001 Acta Materialia inc. Published by Elsevier Science Lid. All rights reserved.