In the present study, the grain growth behavior of Al2O3/NiAl2O4 compo
site is compared with that of Al2O3 and of NiAl2O4. Duplex Al2O4/NiAl2
O4 composite shows strong resistance to coarsening. The activation ene
rgy for the grain growth of monolithic Al2O3 is the same as that of Al
2O3 in composite. However, the activation energy for the grain growth
of NiAl2O4 is changed as NiAl2O4 is surrounded by Al2O3. The shape of
Al2O3 grains in composite is also different from that of Al2O3 in mono
lithic alumina. The coarsening of one phase in the composite is thus c
onstrained by the presence of another phase.