Microhardness measurement of unirradiated and irradiated beryllium oxide.

Abstract

The measured Knoop hardness of beryllium oxide was found to depend on both the indenter load and the orientation of grains within the matrix. Single crystal measurements showed that both prism and basal planes exhibit hardness anisotropy, with a two— and sixfold symmetry respectively. All irradiated specimens except those of lowest density showed irradiation hardening. It is shown that density predominates over such properties as grain size, fabrication methods and source of supply, in controlling the initial hardness of the material, and the rate and extent of the irradiation hardening. No correlation was evident between the extent of irradiation, hardening and observable microcracking.