In the present study, the interfacial structure of nickel particle-rei
nforced alumina composites prepared by a gas reduction process and by
reactive sintering is examined by analytical electron microscopy. Amor
phous carbon films at the interface and graphite inclusions within the
nickel inclusions can be found in products from gas reduction and fro
m reaction sintering, respectively. The microstructural variation resu
lts in different amounts of toughness enhancement. Possible explanatio
ns for the resulting microstructure and toughness differences are prop
osed.