The strength of irradiated magnesium oxide

Abstract
Magnesium oxide single crystals have been irradiated in a reactor to neutron doses in the range 2 × 1019 to 2 × 1020 n.v.t. > 1 Mev. Any irradiation in this dose range prevents slip occurring below a stress of at least 1·3 × 102 Kg mm−2 which was the maximum fracture stress observed (cf. 10 Kg mm−2 as a typical flow stress before irradiation). The source of fracture is sometimes associated with pits produced by polishing and sometimes with impurity precipitates within the body of the crystal.