Neutron irradiation of polycrystalline yttrium aluminate garnet, magnesium aluminate spinel and α-alumina

Polycrystalline pellets of yttrium aluminate garnet (Y3Al5O12), magnesium aluminate spinel (MgAl2O4) and alpha-alumina (alpha-Al2O3) have been irradiated in the high flux reactor (HFR) at Petten to a neutron fluence of 1.7 x 10(26) m(-2) (E > 0.1 MeV) at a temperature of about 815 K. Volume changes smaller than 1% have been measured for Y3Al5O12 and MgAl2O4. Transmission electron microscopy (TEM) results of Y3Al5O12 show no difference between the unirradiated TEM samples and neutron-irradiated samples. For MgAl2O4, dislocation loops in some grains are found in the irradiated samples. TEM results of Al2O3 show a dense network of dislocation loops after neutron irradiation. The increase in volume is 4.2% for a neutron fluence of 1.7 x 10(26) m(-2). (C) 1999 Elsevier Science B.V. All rights reserved.