Strength of neutron-irradiated high-quality 3D carbon fiber composite

The effects of neutron irradiation to 10 dpa at 500 and 800 °C on a high-quality three-dimensional balanced weave composite (FMI-222) is presented. Strength and dimensional stability for this system is compared to earlier work on this material, at lower dose, and contrasted with that of a well studied isotropic graphite (POCO AXF-5Q) irradiated at identical conditions. For both irradiation temperatures the composite strength in bending is substantially increased. While both irradiation temperatures cause contraction along the bend bar axis, the amount of contraction is greater for the higher temperature irradiation. Moreover, for the 500 °C irradiation the corresponding decrease in volume is observed, though an apparent large increase in volume occurs for the 800 °C irradiated composite. This departure from isotropic dimensional change is explained in terms of fiber dimensional stability model previously presented.