Deformation on the grain boundaries and mechanical properties of niobium irradiated by neutrons and α-particles

The effect of neutron and alpha-particle irradiation on mechanical properties and grain boundary deformation of niobium samples is investigated. Part of the samples was irradiated in the WWR-K reactor up to the fluence of 5.5 x 1022 n/M2 (E > 0.1 MeV), the other part - in the U-150 isochronous cyclotron by α-particles with initial energy of 50 MeV. Irradiation temperature in both cases did not exceed 80 deg C. Tensile tests and subsequent studies of changes in microrelief and microstructural surface of the samples are carried out. The conclusion is made that preliminary irradiation intensifies the grain boundary slip, which alongside with accomodation processes is one of the main factors, controlling the high-temperature plasticity and fracture of niobium