Grain boundary deformation in neutron irradiated nickel

The authors studied grain boundary deformation in nickel irradiated with neutrons in a VVR-K reactor and mechanically tested at different temperatures and various neutron fluences. The degree of radiation embrittlement was found to be significant. Results show that the general nature of intergranular displacement occurred in the form of relative sliding and mutual rotation of grains. Neutron irradiation was also found to suppress grain boundary migration. These conditions are assumed to cause the formation of grain boundary microcracks during high temperature tensile deformation. The microcracks increase with increasing deformation and merge together to form a potential main crack leading to ductility loss and intergranular fracture