Fluorescence spectroscopy analysis of Al–Al2O3 composites with coarse interpenetrating networks

Fluorescence microprobe spectroscopy was used to characterize the stress fields that develop within an interpenetrating Al–Al2O3 composite resulting from both the thermal expansion mismatch during sample processing, and from an external applied load. The 30 vol% Al–70 vol% Al2O3 composite that was investigated had an aluminum and alumina phase feature size of 50–100 lm. The residual thermal compressive stress measured in the alumina was ~40–340 MPa. The effect of varying the metal ligament size on the residual stress distribution is discussed. Additionally, the application of an external load caused a non-uniform stress distribution to develop within the alumina regions around the crack-tip, which was attributed to microstructure inhomogeneities. The crack was further extended and the influence of the stress distribution within the alumina regions on the crack extension direction is briefly discussed.