Toughening in composites of Al2O3 reinforced with Al

Abstract

The toughening of Al₂O₃ by Al has been investigated, using electron microscopy to provide in sit measurements of the microstructural parameters that govern ductile ligament toughening. The results are used to compare the measured toughness with values calculated for ligaments that exhibit limited debonding during ductile rupture. Good agreement confirms that toughening is dominated by the plastic work expended in the ductile rupture of ligaments stretched between the crack surfaces. Furthermore, it is demonstrated that in situ measurements are needed to assign the appropriate flow stress, because of the occurrence of coupled precipitation/solution hardening, and to ascertain the extent of the plastic stretch.