EFFECT OF HEAT TREATMENT AND IRRADIATION BY NEUTRONS ON THE PHYSICAL AND MECHANICAL PROPERTIES OF BERYLLIUM OXIDE SINTERED UNDER PRESSURE

Journal Article · Sat Jul 01 04:00:00 EDT 1961 · J. Nuclear Materials

DOI:https://doi.org/10.1016/0022-3115(61)90124-6· OSTI ID:4839937

Elston, J; Labbe, C

The fabrication of blocks of beryllium oxide by sintering under load is briefly described. This method permits dense compacts of "nuclear purity" to be obtained. Annealing at 1300 deg C relieves internal stresses in blocks which have been made by sintering under load. Prolonged heat treatment at 1400 deg C results in an appreciable reduction of the density and deterioration of the mechanical properties of these compacts; this is associated with the precipitation of bubbles of gas at grain boundaries. The effects were examined of neutron irradiation in a reactor on the crystal parameters of beryllium oxide, the length of specimens, the thermal conductivity, and the compressive strength of blocks made by sintering under load. These tests showed a sensitive influence of the oxide density and the irradiation temperature on the stability of the material under neutron irradiation. At a temperature below 100 deg C, irradiation produces a highly anisotropic dilatation of the crystal lattice. ( DELTA c/c) is about ten times greater than ( DELTA a/a). This distortion is the cause of the deterioration of the mechanical properties of the compacts. An irradiation of 2 x 10/sup 20/ neutrons/cm/sup 2/ leads to complete disintegration of the compacts (for an irradiation temperature below 100 deg C). Suitable post- irradiation heat treatment of beryllium oxide compacts made by sintering under load permit the original characteristics of the material to be restored approximately; however, liberation of gas in a compact can lead to a serious deterioration of mechanical properties. Agglomeration of gas at grain boundaries is detectable from 1000 deg C upwards in irradiated compacts. (auth)

• Research Organization: Centre d'Etudes Nucleaires, Saclay, France
• NSA Number: NSA-15-031275
• OSTI ID: 4839937
• Journal Information: J. Nuclear Materials, Journal Name: J. Nuclear Materials Vol. Vol: 4
• Country of Publication: Country unknown/Code not available
• Language: French

Related Subjects

ANISOTROPY
ANNEALING
BERYLLIUM OXIDES
BUBBLES
CRYSTALS
DECOMPOSITION
DEFORMATION
DENSITY
EXPANSION
FABRICATION
GASES
GRAIN BOUNDARIES
HEAT TREATMENTS
HIGH TEMPERATURE
IRRADIATION
LATTICES
MECHANICAL PROPERTIES
METALS, CERAMICS, AND OTHER MATERIALS
NEUTRON BEAMS
PRECIPITATION
PRESSURE
RADIATION EFFECTS
SINTERING
STABILITY
STRESSES
TEMPERATURE
TENSILE PROPERTIES
THERMAL CONDUCTIVITY